diff --git a/doc/administration/settings/visibility_and_access_controls.md b/doc/administration/settings/visibility_and_access_controls.md
index 0ad0f4c5dbd992a0f7c2d9f31df9eee90b0b216b..9d888d673e6daa6a951c2755a916600a597a9a57 100644
--- a/doc/administration/settings/visibility_and_access_controls.md
+++ b/doc/administration/settings/visibility_and_access_controls.md
@@ -98,6 +98,7 @@ To disable the restriction:
 - Enabled delayed deletion for projects by default [on GitLab.com](https://gitlab.com/gitlab-org/gitlab/-/issues/393622) and [on GitLab Self-Managed](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/119606) in GitLab 16.0.
 - [Changed to default behavior for groups](https://gitlab.com/gitlab-org/gitlab/-/issues/389557) on the Premium and Ultimate tier in GitLab 16.0.
 - [Moved](https://gitlab.com/groups/gitlab-org/-/epics/17208) from GitLab Premium to GitLab Free in 18.0.
+- [Instance setting](#immediate-deletion) to allow immediate deletion for groups or projects scheduled for deletion [introduced](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/205556) in GitLab 18.5. Enabled by default. Disabled on GitLab.com and Dedicated.
 
 {{< /history >}}
 
@@ -124,8 +125,10 @@ To configure deletion protection for groups and projects:
 
 {{< history >}}
 
-- [Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/561680) in GitLab 18.4 [with a flag](../../administration/feature_flags/_index.md) named `disallow_immediate_deletion`. Disabled by default.
-- [Replaced](https://gitlab.com/gitlab-org/gitlab/-/issues/569453) in GitLab 18.5 by an instance setting to allow immediate deletion of groups and projects scheduled for deletion. [Controlled by a flag](../feature_flags/_index.md) named `allow_immediate_namespaces_deletion`. Feature flag is disabled by default.
+- Instance setting to allow immediate deletion for groups or projects scheduled for deletion
+  [introduced](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/205556) in GitLab 18.5
+  [with a flag](../feature_flags/_index.md) named `allow_immediate_namespaces_deletion`.
+  Enabled by default on self-managed, but disabled on GitLab.com and Dedicated.
 
 {{< /history >}}
 
@@ -136,19 +139,20 @@ For more information, see the history.
 
 {{< /alert >}}
 
-Immediately delete groups and projects scheduled for deletion. This action bypasses the configured retention period and deletes groups or projects immediately.
+By default, immediate deletion is allowed for groups and projects marked for deletion. This allows users
+to effectively bypass the configured retention period and delete groups or projects immediately.
 
-To turn off immediate deletion for groups and projects:
+This can be disabled, so that groups and projects are only deleted automatically after the configured retention period:
 
 1. On the left sidebar, at the bottom, select **Admin**.
 1. Select **Settings** > **General**.
 1. Expand **Visibility and access controls**.
-1. Under **Immediate deletion**, clear the checkbox.
+1. Scroll to **Immediate deletion** and uncheck the checkbox.
 1. Select **Save changes**.
 
 {{< alert type="note" >}}
 
-Administrators can still delete groups and projects when this setting is turned off.
+Administrators can always immediately delete groups and projects through the Admin pages.
 
 {{< /alert >}}
 
diff --git a/doc/api/groups.md b/doc/api/groups.md
index 5594bd323f55db1e1eaf06c4288a7dcc0db29f72..4219d6aa65a9d1540642189c562eebf4af7589a4 100644
--- a/doc/api/groups.md
+++ b/doc/api/groups.md
@@ -1372,7 +1372,11 @@ curl --request POST --header "PRIVATE-TOKEN: <your_access_token>" \
 {{< history >}}
 
 - Marking groups for deletion [available](https://gitlab.com/groups/gitlab-org/-/epics/17208) on Free tier in GitLab 18.0.
-- `permanently_remove` was [deprecated](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/201957) in GitLab 18.4 [with a flag](../administration/feature_flags/_index.md) named `disallow_immediate_deletion`.
+- Since GitLab 18.5, `permanently_remove` is [not permitted](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/205572)
+  when the immediate deletion
+  [instance setting](../administration/settings/visibility_and_access_controls.md#immediate-deletion)
+  is disabled (behind [a feature flag](../administration/feature_flags/_index.md) named `allow_immediate_namespaces_deletion`).
+  The setting is enabled by default on self-managed, but disabled on GitLab.com and Dedicated.
 
 {{< /history >}}
 
@@ -1388,14 +1392,23 @@ Marks a group for deletion. Groups are deleted at the end of the retention perio
 
 This endpoint can also immediately delete a subgroup that was previously marked for deletion.
 
+{{< alert type="warning" >}}
+
+On GitLab.com, after a group is deleted, its data is retained for 30 days, and immediate deletion is not available.
+If you really need to delete a group immediately on GitLab.com, you can open a [support ticket](https://about.gitlab.com/support/).
+
+{{< /alert >}}
+
 ```plaintext
 DELETE /groups/:id
 ```
 
 Parameters:
 
+| Attribute | Type           | Required | Description |
+|-----------|----------------|----------|-------------|
 | `id`                 | integer or string | yes      | The ID or [URL-encoded path](rest/_index.md#namespaced-paths) of the group. |
-| `permanently_remove` | boolean/string | no       | [Deprecated](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/201957) in GitLab 18.4. If `true`, immediately deletes a subgroup that is already marked for deletion. Cannot delete top-level groups. |
+| `permanently_remove` | boolean/string | no       | If `true`, immediately deletes a subgroup that is already marked for deletion. Cannot delete top-level groups. Disabled on GitLab.com and Dedicated. |
 | `full_path`          | string         | no       | The full path to the subgroup. Used to confirm deletion of the subgroup. If `permanently_remove` is `true`, this attribute is required. To find the subgroup path, see the [group details](groups.md#get-a-single-group). |
 
 The response is `202 Accepted` if the user has authorization.
diff --git a/doc/api/projects.md b/doc/api/projects.md
index 2210fec19e444d936372ca3f3c5cb5a6c7919b01..2c55de22877e6408ffb836bcb6d8cab9a0a882e2 100644
--- a/doc/api/projects.md
+++ b/doc/api/projects.md
@@ -2183,21 +2183,30 @@ Example response:
 
 - Immediately deleting projects was [enabled on GitLab.com and GitLab Self-Managed](https://gitlab.com/gitlab-org/gitlab/-/issues/396500) in GitLab 15.11.
 - [Marking project for deletion was moved](https://gitlab.com/groups/gitlab-org/-/epics/17208) from GitLab Premium to GitLab Free in 18.0.
-- `permanently_remove` was [deprecated](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/201957) in GitLab 18.4 [with a flag](../administration/feature_flags/_index.md) named `disallow_immediate_deletion`.
+- Since GitLab 18.5, `permanently_remove` is [not permitted](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/205572)
+  when the immediate deletion
+  [instance setting](../administration/settings/visibility_and_access_controls.md#immediate-deletion)
+  is disabled (behind [a feature flag](../administration/feature_flags/_index.md) named `allow_immediate_namespaces_deletion`).
+  The setting is enabled by default on self-managed, but disabled on GitLab.com and Dedicated.
 
 {{< /history >}}
 
-Delete a project. This endpoint:
+Prerequisites:
+
+- You must be an administrator or have the Owner role for the project.
+
+Marks a project for deletion. Projects are deleted at the end of the retention period:
+
+- On GitLab.com, projects are retained for 30 days.
+- On GitLab Self-Managed, the retention period is controlled by the
+  [instance settings](../administration/settings/visibility_and_access_controls.md#deletion-protection).
 
-- Deletes a project including all associated resources, including issues and merge requests.
-- Marks the project for deletion. On GitLab.com, by default, the deletion happens 30 days later. On GitLab Self-Managed,
-  the retention period depends on the [instance settings](../administration/settings/visibility_and_access_controls.md#deletion-protection).
-- Deletes project immediately if the project is marked for deletion (GitLab 15.11 and later).
+This endpoint can also immediately delete a project that was previously marked for deletion.
 
 {{< alert type="warning" >}}
 
-The option to delete projects immediately from deletion protection settings in the **Admin** area was
-[deprecated](https://gitlab.com/gitlab-org/gitlab/-/issues/389557) in GitLab 15.9 and removed in GitLab 16.0.
+On GitLab.com, after a project is deleted, its data is retained for 30 days, and immediate deletion is not available.
+If you really need to delete a project immediately on GitLab.com, you can open a [support ticket](https://about.gitlab.com/support/).
 
 {{< /alert >}}
 
@@ -2211,7 +2220,7 @@ Supported attributes:
 |:---------------------|:------------------|:---------|:------------|
 | `id`                 | integer or string | Yes      | The ID or [URL-encoded path of the project](rest/_index.md#namespaced-paths). |
 | `full_path`          | string            | no       | Full path of project to use with `permanently_remove`. [Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/396500) in GitLab 15.11 for Premium and Ultimate only and moved to GitLab Free in 18.0. To find the project path, use `path_with_namespace` from [get single project](projects.md#get-a-single-project). |
-| `permanently_remove` | boolean/string    | no       | [Deprecated](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/201957) in GitLab 18.4. Immediately deletes a project if it is marked for deletion. [Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/396500) in GitLab 15.11 for Premium and Ultimate only and moved to GitLab Free in 18.0. |
+| `permanently_remove` | boolean/string    | no       | Immediately deletes a project if it is marked for deletion. [Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/396500) in GitLab 15.11 for Premium and Ultimate only and moved to GitLab Free in 18.0. Disabled on GitLab.com and Dedicated. |
 
 ### Restore a project marked for deletion
 
diff --git a/lib/api/groups.rb b/lib/api/groups.rb
index ff048e6ee8e54255808561bfac94d09c4f950624..b96df3c60e796018422c5db13e854c4459f7e5bb 100644
--- a/lib/api/groups.rb
+++ b/lib/api/groups.rb
@@ -173,8 +173,8 @@ def present_groups_with_pagination_strategies(params, groups)
       end
 
       def immediately_delete_subgroup_error(group)
-        if Feature.enabled?(:disallow_immediate_deletion, current_user)
-          '`permanently_remove` option is not available anymore (behind the :disallow_immediate_deletion feature flag).'
+        if !Gitlab::CurrentSettings.allow_immediate_namespaces_deletion_for_user?(current_user)
+          '`permanently_remove` option is not permitted on this instance.'
         elsif !group.subgroup?
           '`permanently_remove` option is only available for subgroups.'
         elsif !group.self_deletion_scheduled?
diff --git a/lib/api/projects.rb b/lib/api/projects.rb
index ca862b486b072f50bfc2837c8295c9da6ccb7ac3..6270eda286cc81fb12187ecadc3c33f0fad75932 100644
--- a/lib/api/projects.rb
+++ b/lib/api/projects.rb
@@ -86,9 +86,8 @@ def support_order_by_similarity!(attrs)
       end
 
       def immediately_delete_project_error(project)
-        # Admin frontend uses this endpoint to force-delete projects
-        if Feature.enabled?(:disallow_immediate_deletion, current_user) && !current_user.can_admin_all_resources?
-          '`permanently_remove` option is not available anymore (behind the :disallow_immediate_deletion feature flag).'
+        if !Gitlab::CurrentSettings.allow_immediate_namespaces_deletion_for_user?(current_user)
+          '`permanently_remove` option is not permitted on this instance.'
         elsif !project.self_deletion_scheduled?
           'Project must be marked for deletion first.'
         elsif project.full_path != params[:full_path]
diff --git a/spec/requests/api/groups_spec.rb b/spec/requests/api/groups_spec.rb
index d1ef32ae5df9342f85dc7459dc82caedc31e586a..9690fe8a21906f4b01ed3d979772538f03acb12c 100644
--- a/spec/requests/api/groups_spec.rb
+++ b/spec/requests/api/groups_spec.rb
@@ -3346,27 +3346,30 @@ def make_upload_request
   describe "DELETE /groups/:id" do
     let(:group) { group1 }
     let(:user) { user1 }
+    let(:admin_mode) { false }
     let(:params) { {} }
 
-    subject { delete api("/groups/#{group.id}", user), params: params }
+    subject(:api_request) { delete api("/groups/#{group.id}", user, admin_mode: admin_mode), params: params }
 
     shared_examples_for 'immediately enqueues the job to delete the group' do
       it 'immediately enqueues the job to delete the group', :clean_gitlab_redis_queues do
         Sidekiq::Testing.fake! do
-          expect { subject }.to change(GroupDestroyWorker.jobs, :size).by(1)
+          expect { api_request }.to change(GroupDestroyWorker.jobs, :size).by(1)
         end
 
         expect(response).to have_gitlab_http_status(:accepted)
       end
     end
 
-    shared_examples_for 'does not immediately enqueues the job to delete the group' do |error_message|
+    shared_examples_for 'does not immediately enqueues the job to delete the group' do
+      let(:expected_http_status) { :bad_request }
+
       it 'does not immediately enqueues the job to delete the group', :clean_gitlab_redis_queues do
         Sidekiq::Testing.fake! do
-          expect { subject }.not_to change(GroupDestroyWorker.jobs, :size)
+          expect { api_request }.not_to change(GroupDestroyWorker.jobs, :size)
         end
 
-        expect(response).to have_gitlab_http_status(:bad_request)
+        expect(response).to have_gitlab_http_status(expected_http_status)
         expect(json_response['message']).to eq(error_message)
       end
     end
@@ -3374,7 +3377,7 @@ def make_upload_request
     shared_examples_for 'marks group for delayed deletion' do
       it 'marks group for delayed deletion', :clean_gitlab_redis_queues do
         Sidekiq::Testing.fake! do
-          expect { subject }.not_to change(GroupDestroyWorker.jobs, :size)
+          expect { api_request }.not_to change(GroupDestroyWorker.jobs, :size)
         end
 
         group.reload
@@ -3412,64 +3415,92 @@ def make_upload_request
       let(:params) { { permanently_remove: true } }
 
       context 'if group is a subgroup' do
-        let(:subgroup) { create(:group, parent: group) }
+        let(:parent_group) { create(:group) }
 
-        subject { delete api("/groups/#{subgroup.id}", user), params: params }
-
-        context 'forbidden by the :disallow_immediate_deletion feature flag' do
-          it_behaves_like 'does not immediately enqueues the job to delete the group',
-            '`permanently_remove` option is not available anymore (behind the :disallow_immediate_deletion feature flag).'
+        before do
+          group.update!(parent: parent_group)
         end
 
-        context 'when the :disallow_immediate_deletion feature flag is disabled' do
+        describe 'when the :allow_immediate_namespaces_deletion application setting is false' do
           before do
-            stub_feature_flags(disallow_immediate_deletion: false)
+            stub_application_setting(allow_immediate_namespaces_deletion: false)
           end
 
-          context 'when group is not marked for deletion' do
-            it_behaves_like 'does not immediately enqueues the job to delete the group', 'Group must be marked for deletion first.'
+          it_behaves_like 'does not immediately enqueues the job to delete the group' do
+            let(:error_message) { '`permanently_remove` option is not permitted on this instance.' }
           end
 
-          context 'when group is already marked for deletion' do
-            before do
-              create(:group_deletion_schedule, group: subgroup, marked_for_deletion_on: Date.current)
-            end
+          context 'when current user is an admin' do
+            let_it_be(:user) { admin }
+            let(:admin_mode) { true }
+
+            context 'when group is already marked for deletion' do
+              let(:params) { { permanently_remove: true, full_path: group.full_path } }
 
-            context 'when full_path param is not passed' do
-              it_behaves_like 'does not immediately enqueues the job to delete the group',
-                '`full_path` is incorrect. You must enter the complete path for the subgroup.'
+              before do
+                create(:group_deletion_schedule, group: group, marked_for_deletion_on: Date.current)
+                group.add_owner(admin)
+              end
+
+              it_behaves_like 'immediately enqueues the job to delete the group'
+
+              context 'when admin_mode is false' do
+                let(:admin_mode) { false }
+
+                it_behaves_like 'does not immediately enqueues the job to delete the group' do
+                  let(:error_message) { '`permanently_remove` option is not permitted on this instance.' }
+                end
+              end
             end
+          end
+        end
 
-            context 'when full_path param is not equal to full_path' do
-              let(:params) { { permanently_remove: true, full_path: subgroup.path } }
+        context 'when group is not marked for deletion' do
+          it_behaves_like 'does not immediately enqueues the job to delete the group' do
+            let(:error_message) { 'Group must be marked for deletion first.' }
+          end
+        end
 
-              it_behaves_like 'does not immediately enqueues the job to delete the group',
-                '`full_path` is incorrect. You must enter the complete path for the subgroup.'
+        context 'when group is already marked for deletion' do
+          before do
+            create(:group_deletion_schedule, group: group, marked_for_deletion_on: Date.current)
+          end
+
+          context 'when full_path param is not passed' do
+            it_behaves_like 'does not immediately enqueues the job to delete the group' do
+              let(:error_message) { '`full_path` is incorrect. You must enter the complete path for the subgroup.' }
             end
+          end
 
-            context 'when the full_path param is passed and it matches the full path of subgroup' do
-              let(:params) { { permanently_remove: true, full_path: subgroup.full_path } }
+          context 'when full_path param is not equal to full_path' do
+            let(:params) { { permanently_remove: true, full_path: group.path } }
 
-              it_behaves_like 'immediately enqueues the job to delete the group'
+            it_behaves_like 'does not immediately enqueues the job to delete the group' do
+              let(:error_message) { '`full_path` is incorrect. You must enter the complete path for the subgroup.' }
             end
           end
-        end
-      end
 
-      context 'if group is not a subgroup' do
-        subject { delete api("/groups/#{group.id}", user), params: params }
+          context 'when the full_path param is passed and it matches the full path of subgroup' do
+            let(:params) { { permanently_remove: true, full_path: group.full_path } }
 
-        context 'forbidden by the :disallow_immediate_deletion feature flag' do
-          it_behaves_like 'does not immediately enqueues the job to delete the group',
-            '`permanently_remove` option is not available anymore (behind the :disallow_immediate_deletion feature flag).'
+            it_behaves_like 'immediately enqueues the job to delete the group'
+          end
         end
+      end
 
-        context 'when the :disallow_immediate_deletion feature flag is disabled' do
+      context 'if group is not a subgroup' do
+        describe 'when the :allow_immediate_namespaces_deletion application setting is false' do
           before do
-            stub_feature_flags(disallow_immediate_deletion: false)
+            stub_application_setting(allow_immediate_namespaces_deletion: false)
           end
 
-          it_behaves_like 'does not immediately enqueues the job to delete the group', '`permanently_remove` option is only available for subgroups.'
+          it_behaves_like 'does not immediately enqueues the job to delete the group' do
+            let(:error_message) { '`permanently_remove` option is not permitted on this instance.' }
+          end
+        end
+
+        it_behaves_like 'does not immediately enqueues the job to delete the group' do
+          let(:error_message) { '`permanently_remove` option is only available for subgroups.' }
         end
       end
     end
@@ -3481,7 +3512,7 @@ def make_upload_request
       end
 
       it 'returns an error' do
-        subject
+        api_request
 
         expect(response).to have_gitlab_http_status(:bad_request)
         expect(json_response['message']).to eq('error')
diff --git a/spec/requests/api/projects_spec.rb b/spec/requests/api/projects_spec.rb
index a19ec31884c0ccd584d66a4a7fd655228e112f93..818a47ad05d0b6fb9d2e806633844819be424ef7 100644
--- a/spec/requests/api/projects_spec.rb
+++ b/spec/requests/api/projects_spec.rb
@@ -5566,6 +5566,10 @@ def request_with_second_scope
 
   describe 'DELETE /projects/:id' do
     let(:path) { "/projects/#{project.id}" }
+    let(:admin_mode) { false }
+    let(:params) { {} }
+
+    subject(:api_request) { delete api(path, user, admin_mode: admin_mode), params: params }
 
     it_behaves_like 'DELETE request permissions for admin mode' do
       let(:success_status_code) { :accepted }
@@ -5574,7 +5578,7 @@ def request_with_second_scope
 
     context 'when authenticated as user' do
       it 'removes project' do
-        delete api(path, user)
+        api_request
 
         expect(response).to have_gitlab_http_status(:accepted)
         expect(json_response['message']).to eql('202 Accepted')
@@ -5604,39 +5608,30 @@ def request_with_second_scope
     end
 
     context 'when authenticated as admin' do
-      it 'removes any existing project' do
-        delete api("/projects/#{project.id}", admin, admin_mode: true)
-
-        expect(response).to have_gitlab_http_status(:accepted)
-        expect(json_response['message']).to eql('202 Accepted')
-      end
-
-      it 'does not remove a non existing project' do
-        delete api("/projects/#{non_existing_record_id}", admin, admin_mode: true)
-        expect(response).to have_gitlab_http_status(:not_found)
-      end
-
       it_behaves_like '412 response' do
         let(:success_status) { 202 }
-        subject(:request) { api("/projects/#{project.id}", admin, admin_mode: true) }
+        subject(:request) { api(path, admin, admin_mode: true) }
       end
     end
 
-    shared_examples 'deletes project immediately' do |admin_mode = false|
+    shared_examples 'deletes project immediately' do
       it :aggregate_failures do
         expect(::Projects::DestroyService).to receive(:new).with(project, user, {}).and_call_original
 
-        delete api(path, user, admin_mode: admin_mode), params: params
+        api_request
+
         expect(response).to have_gitlab_http_status(:accepted)
       end
     end
 
-    shared_examples 'immediately delete project error' do |admin_mode = false, expected_http_status = :bad_request|
+    shared_examples 'immediately delete project error' do
+      let(:expected_http_status) { :bad_request }
+
       it :aggregate_failures do
         expect(::Projects::DestroyService).not_to receive(:new)
         expect(::Projects::MarkForDeletionService).not_to receive(:new)
 
-        delete api(path, user, admin_mode: admin_mode), params: params
+        api_request
 
         expect(response).to have_gitlab_http_status(expected_http_status)
         expect(Gitlab::Json.parse(response.body)['message']).to eq(error_message)
@@ -5646,12 +5641,11 @@ def request_with_second_scope
     context 'for delayed deletion' do
       let_it_be(:group) { create(:group) }
       let_it_be_with_reload(:project) { create(:project, group: group, owners: user) }
-      let(:params) { {} }
 
       it 'marks the project for deletion' do
         expect(::Projects::MarkForDeletionService).to receive(:new).with(project, user, {}).and_call_original
 
-        delete api(path, user), params: params
+        api_request
 
         expect(response).to have_gitlab_http_status(:accepted)
         expect(project.reload.self_deletion_scheduled?).to be_truthy
@@ -5678,7 +5672,7 @@ def request_with_second_scope
         message = 'Error'
         expect(::Projects::MarkForDeletionService).to receive_message_chain(:new, :execute).and_return({ status: :error, message: message })
 
-        delete api("/projects/#{project.id}", user)
+        api_request
 
         expect(response).to have_gitlab_http_status(:bad_request)
         expect(json_response["message"]).to eq(message)
@@ -5689,64 +5683,74 @@ def request_with_second_scope
           params.merge!(permanently_remove: true)
         end
 
-        context 'forbidden by the :disallow_immediate_deletion feature flag' do
-          let(:error_message) { '`permanently_remove` option is not available anymore (behind the :disallow_immediate_deletion feature flag).' }
+        describe 'when the :allow_immediate_namespaces_deletion application setting is false' do
+          before do
+            stub_application_setting(allow_immediate_namespaces_deletion: false)
+          end
 
-          it_behaves_like 'immediately delete project error'
-        end
+          it_behaves_like 'immediately delete project error' do
+            let(:error_message) { '`permanently_remove` option is not permitted on this instance.' }
+          end
 
-        context 'when current user is an admin' do
-          let_it_be(:user) { admin }
+          context 'when current user is an admin' do
+            let_it_be(:user) { admin }
+            let(:admin_mode) { true }
 
-          context 'when project is already marked for deletion' do
-            before do
-              project.update!(archived: true, marked_for_deletion_at: 1.day.ago, deleting_user: user)
-              params.merge!(full_path: project.full_path)
-            end
+            context 'when project is already marked for deletion' do
+              before do
+                project.update!(marked_for_deletion_at: 1.day.ago, deleting_user: admin)
+                params[:full_path] = project.full_path
+                project.add_owner(admin)
+              end
 
-            it_behaves_like 'deletes project immediately', true
+              it_behaves_like 'deletes project immediately'
 
-            context 'when admin_mode is false' do
-              let(:error_message) { '404 Project Not Found' }
+              context 'when admin_mode is false' do
+                let(:admin_mode) { false }
 
-              it_behaves_like 'immediately delete project error', false, :not_found
+                it_behaves_like 'immediately delete project error' do
+                  let(:error_message) { '`permanently_remove` option is not permitted on this instance.' }
+                end
+              end
             end
           end
         end
 
-        context 'when the :disallow_immediate_deletion feature flag is disabled' do
-          before do
-            stub_feature_flags(disallow_immediate_deletion: false)
-          end
+        context 'when project is not marked for deletion' do
+          let(:error_message) { 'Project must be marked for deletion first.' }
 
-          context 'when project is not marked for deletion' do
-            let(:error_message) { 'Project must be marked for deletion first.' }
+          it_behaves_like 'immediately delete project error'
+        end
 
-            it_behaves_like 'immediately delete project error'
+        context 'when project is already marked for deletion' do
+          before do
+            project.update!(archived: true, marked_for_deletion_at: 1.day.ago, deleting_user: user)
           end
 
-          context 'when project is already marked for deletion' do
+          context 'with correct project full path' do
             before do
-              project.update!(archived: true, marked_for_deletion_at: 1.day.ago, deleting_user: user)
+              params.merge!(full_path: project.full_path)
             end
 
-            context 'with correct project full path' do
+            it_behaves_like 'deletes project immediately'
+
+            context 'when the allow_immediate_namespaces_deletion FF is disabled' do
               before do
-                params.merge!(full_path: project.full_path)
+                stub_feature_flags(allow_immediate_namespaces_deletion: false)
               end
 
               it_behaves_like 'deletes project immediately'
             end
+          end
 
-            context 'with incorrect project full path' do
-              let(:error_message) { '`full_path` is incorrect. You must enter the complete path for the project.' }
-
-              before do
-                params.merge!(full_path: "#{project.full_path}-wrong-path")
-              end
+          context 'with incorrect project full path' do
+            let(:error_message) { '`full_path` is incorrect. You must enter the complete path for the project.' }
 
-              it_behaves_like 'immediately delete project error'
+            before do
+              params.merge!(full_path: "#{project.full_path}-wrong-path")
             end
+
+            it_behaves_like 'immediately delete project error'
           end
         end
       end