Change access levels from Protected Branch API

Following the documentation https://docs.gitlab.com/14.9/ee/api/protected_branches.html there is an option to change access level for the protection branches. See "Example with allow to push and allow to merge access" in the document. However, when trying to do this we have error "Protected branch 'master' already exists", so in order to change the level we have to delete the protection first. Please make an ability to change the access level for the protected branch without delete the protection. Thanks.