diff --git a/app/models/namespace.rb b/app/models/namespace.rb
index 260ba9ea4a58395a390a7f9b8a8c0699e842518a..b662aa22242d0d59ac755a09d899fbfd519e3c37 100644
--- a/app/models/namespace.rb
+++ b/app/models/namespace.rb
@@ -11,6 +11,9 @@ class Namespace < ApplicationRecord
   include FeatureGate
   include FromUnion
   include Gitlab::Utils::StrongMemoize
+  include IgnorableColumns
+
+  ignore_column :plan_id, remove_with: '12.10', remove_after: '2020-05-22'
 
   # Prevent users from creating unreasonably deep level of nesting.
   # The number 20 was taken based on maximum nesting level of
diff --git a/config/pseudonymizer.yml b/config/pseudonymizer.yml
index 7b5f8aad25569c0259cefe6d7d27d6033151b558..195506ac4a150b5c38cc982e61edb4e2947e6724 100644
--- a/config/pseudonymizer.yml
+++ b/config/pseudonymizer.yml
@@ -239,7 +239,6 @@ tables:
     - repository_size_limit
     - require_two_factor_authentication
     - two_factor_grace_period
-    - plan_id
     - project_creation_level
   members:
     whitelist:
diff --git a/db/post_migrate/20200324135315_remove_namespace_plan_id.rb b/db/post_migrate/20200324135315_remove_namespace_plan_id.rb
new file mode 100644
index 0000000000000000000000000000000000000000..f20d3dd47f109a73370e9a2ba335278c04c2b66f
--- /dev/null
+++ b/db/post_migrate/20200324135315_remove_namespace_plan_id.rb
@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+
+class RemoveNamespacePlanId < ActiveRecord::Migration[6.0]
+  DOWNTIME = false
+
+  def up
+    remove_column :namespaces, :plan_id
+  end
+
+  def down
+    add_column :namespaces, :plan_id, :integer
+  end
+end
diff --git a/db/structure.sql b/db/structure.sql
index 90585a157cfad352e8dbf27f021968f03672854b..43e268becdfbec3d7a955cd7ed5825df0141db50 100644
--- a/db/structure.sql
+++ b/db/structure.sql
@@ -4005,7 +4005,6 @@ CREATE TABLE public.namespaces (
     require_two_factor_authentication boolean DEFAULT false NOT NULL,
     two_factor_grace_period integer DEFAULT 48 NOT NULL,
     cached_markdown_version integer,
-    plan_id integer,
     project_creation_level integer,
     runners_token character varying,
     trial_ends_on timestamp with time zone,
@@ -9621,8 +9620,6 @@ CREATE INDEX index_namespaces_on_path ON public.namespaces USING btree (path);
 
 CREATE INDEX index_namespaces_on_path_trigram ON public.namespaces USING gin (path public.gin_trgm_ops);
 
-CREATE INDEX index_namespaces_on_plan_id ON public.namespaces USING btree (plan_id);
-
 CREATE INDEX index_namespaces_on_require_two_factor_authentication ON public.namespaces USING btree (require_two_factor_authentication);
 
 CREATE UNIQUE INDEX index_namespaces_on_runners_token ON public.namespaces USING btree (runners_token);
@@ -10975,9 +10972,6 @@ ALTER TABLE ONLY public.system_note_metadata
 ALTER TABLE ONLY public.merge_requests
     ADD CONSTRAINT fk_fd82eae0b9 FOREIGN KEY (head_pipeline_id) REFERENCES public.ci_pipelines(id) ON DELETE SET NULL;
 
-ALTER TABLE ONLY public.namespaces
-    ADD CONSTRAINT fk_fdd12e5b80 FOREIGN KEY (plan_id) REFERENCES public.plans(id) ON DELETE SET NULL;
-
 ALTER TABLE ONLY public.project_import_data
     ADD CONSTRAINT fk_ffb9ee3a10 FOREIGN KEY (project_id) REFERENCES public.projects(id) ON DELETE CASCADE;
 
@@ -13061,6 +13055,7 @@ COPY "schema_migrations" (version) FROM STDIN;
 20200323134519
 20200324093258
 20200324115359
+20200324135315
 20200325152327
 20200325160952
 20200325183636
diff --git a/ee/app/models/ee/namespace.rb b/ee/app/models/ee/namespace.rb
index 7f70685287dffac74843a0e8da681ae3e476e45f..23818cc3ab8c7a82df53cc9c2430d55d5fdc2b99 100644
--- a/ee/app/models/ee/namespace.rb
+++ b/ee/app/models/ee/namespace.rb
@@ -27,8 +27,6 @@ module Namespace
 
       attr_writer :root_ancestor
 
-      belongs_to :plan
-
       has_one :namespace_statistics
       has_one :gitlab_subscription, dependent: :destroy # rubocop:disable Cop/ActiveRecordDependent
 
@@ -62,7 +60,6 @@ module Namespace
       # Opportunistically clear the +file_template_project_id+ if invalid
       before_validation :clear_file_template_project_id
 
-      validate :validate_plan_name
       validate :validate_shared_runner_minutes_support
 
       validates :max_pages_size,
@@ -293,17 +290,6 @@ def shared_runners_enabled?
       all_projects.with_shared_runners.any?
     end
 
-    # These helper methods are required to not break the Namespace API.
-    def plan=(plan_name)
-      if plan_name.is_a?(String)
-        @plan_name = plan_name # rubocop:disable Gitlab/ModuleWithInstanceVariables
-
-        super(Plan.find_by(name: @plan_name)) # rubocop:disable Gitlab/ModuleWithInstanceVariables
-      else
-        super
-      end
-    end
-
     def memoized_plans=(plans)
       @plans = plans # rubocop: disable Gitlab/ModuleWithInstanceVariables
     end
@@ -396,12 +382,6 @@ def use_elasticsearch?
 
     private
 
-    def validate_plan_name
-      if defined?(@plan_name) && @plan_name.present? && PLANS.exclude?(@plan_name) # rubocop:disable Gitlab/ModuleWithInstanceVariables
-        errors.add(:plan, 'is not included in the list')
-      end
-    end
-
     def validate_shared_runner_minutes_support
       return if shared_runner_minutes_supported?
 
diff --git a/ee/app/models/ee/pages_domain.rb b/ee/app/models/ee/pages_domain.rb
index 564d9daa72508694a36cdddb64166ddd152dc9dc..c2824faeda3e89cc835712ba7d0c29ba143c4edb 100644
--- a/ee/app/models/ee/pages_domain.rb
+++ b/ee/app/models/ee/pages_domain.rb
@@ -5,7 +5,7 @@ module PagesDomain
     extend ActiveSupport::Concern
 
     prepended do
-      scope :with_logging_info, -> { includes(project: [:route, { namespace: [:plan, :gitlab_subscription] }]) }
+      scope :with_logging_info, -> { includes(project: [:route, { namespace: [:gitlab_subscription] }]) }
     end
   end
 end
diff --git a/ee/app/models/plan.rb b/ee/app/models/plan.rb
index 8af4fd94469311acfc046bae40b199340852877e..79b16a83a8f9cf7c920c1f22d063692dccbe958a 100644
--- a/ee/app/models/plan.rb
+++ b/ee/app/models/plan.rb
@@ -13,7 +13,6 @@ class Plan < ApplicationRecord
   DEFAULT_PLANS = [DEFAULT, FREE].freeze
   ALL_HOSTED_PLANS = (PAID_HOSTED_PLANS + [EARLY_ADOPTER]).freeze
 
-  has_many :namespaces
   has_many :hosted_subscriptions, class_name: 'GitlabSubscription', foreign_key: 'hosted_plan_id'
   has_one :limits, class_name: 'PlanLimits'
 
diff --git a/ee/spec/models/ee/namespace_spec.rb b/ee/spec/models/ee/namespace_spec.rb
index d86c1a6dec1ce6570c31a63d61b88b759176834c..5f58c5178d368bc3c8fc4b14020084bcdfaf79f2 100644
--- a/ee/spec/models/ee/namespace_spec.rb
+++ b/ee/spec/models/ee/namespace_spec.rb
@@ -14,7 +14,6 @@
 
   it { is_expected.to have_one(:namespace_statistics) }
   it { is_expected.to have_one(:gitlab_subscription).dependent(:destroy) }
-  it { is_expected.to belong_to(:plan) }
 
   it { is_expected.to delegate_method(:extra_shared_runners_minutes).to(:namespace_statistics) }
   it { is_expected.to delegate_method(:shared_runners_minutes).to(:namespace_statistics) }
@@ -262,33 +261,6 @@
   end
 
   describe 'custom validations' do
-    describe '#validate_plan_name' do
-      let(:group) { build(:group) }
-
-      context 'with a valid plan name' do
-        it 'is valid' do
-          group.plan = create(:bronze_plan)
-
-          expect(group).to be_valid
-        end
-      end
-
-      context 'with an invalid plan name' do
-        it 'is invalid when `unknown`' do
-          group.plan = 'unknown'
-
-          expect(group).not_to be_valid
-          expect(group.errors[:plan]).to include('is not included in the list')
-        end
-
-        it 'is valid for blank strings' do
-          group.plan = ' '
-
-          expect(group).to be_valid
-        end
-      end
-    end
-
     describe '#validate_shared_runner_minutes_support' do
       context 'when changing :shared_runners_minutes_limit' do
         before do
diff --git a/ee/spec/models/plan_spec.rb b/ee/spec/models/plan_spec.rb
index a4bc6cb2d65852063ca256e91a44868c9d0e9a05..7a46760bddc213683e4b2ddf9cee5814cf52fdac 100644
--- a/ee/spec/models/plan_spec.rb
+++ b/ee/spec/models/plan_spec.rb
@@ -3,10 +3,6 @@
 require 'spec_helper'
 
 describe Plan do
-  describe 'associations' do
-    it { is_expected.to have_many(:namespaces) }
-  end
-
   describe '#default?' do
     subject { plan.default? }
 
diff --git a/ee/spec/support/shared_examples/features/gold_trial_callout_shared_examples.rb b/ee/spec/support/shared_examples/features/gold_trial_callout_shared_examples.rb
index 90a6868441867c5c6d8499ddf84696c08bd0d8cd..e8f704936af523e59ab31d2cc265602bbbcd02bf 100644
--- a/ee/spec/support/shared_examples/features/gold_trial_callout_shared_examples.rb
+++ b/ee/spec/support/shared_examples/features/gold_trial_callout_shared_examples.rb
@@ -49,7 +49,6 @@
 
     it 'hides promotion callout if a gold plan is active', :js do
       group = create(:group_with_plan, name: 'gold group', plan: :gold_plan)
-      group.update(plan: group.gitlab_subscription.hosted_plan)
       group.add_owner(user)
 
       visit page_path