Clarify that default branches cannot be deleted

doc/api/settings.md

@@ -248,7 +248,7 @@ listed in the descriptions of the relevant settings.
 | `deactivate_dormant_users`               | boolean          | no                                   | Enable [automatic deactivation of dormant users](../user/admin_area/moderate_users.md#automatically-deactivate-dormant-users). |
 | `default_artifacts_expire_in`            | string           | no                                   | Set the default expiration time for each job's artifacts. |
 | `default_branch_name`                    | string           | no                                   | [Instance-level custom initial branch name](../user/project/repository/branches/default.md#instance-level-custom-initial-branch-name) ([introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/225258) in GitLab 13.2). |
-| `default_branch_protection`              | integer          | no                                   | Determine if developers can push to the default branch. Can take: `0` _(not protected, both developers and maintainers can push new commits, force push, or delete the branch)_, `1` _(partially protected, developers and maintainers can push new commits, but cannot force push, or delete, the branch)_ or `2` _(fully protected, developers cannot push new commits, but maintainers can; no-one can force push or delete the branch)_ as a parameter. Default is `2`. |
+| `default_branch_protection`              | integer          | no                                   | Determine if developers can push to the default branch. Can take: `0` _(not protected, both developers and maintainers can push new commits and force push)_, `1` _(partially protected, developers and maintainers can push new commits, but cannot force push)_ or `2` _(fully protected, developers cannot push new commits, but maintainers can; no one can force push)_ as a parameter. Default is `2`. |
 | `default_ci_config_path`                  | string           | no                                   | Default CI/CD configuration file and path for new projects (`.gitlab-ci.yml` if not set). |
 | `default_group_visibility`               | string           | no                                   | What visibility level new groups receive. Can take `private`, `internal` and `public` as a parameter. Default is `private`. |
 | `default_project_creation`               | integer          | no                                   | Default project creation protection. Can take: `0` _(No one)_, `1` _(Maintainers)_ or `2` _(Developers + Maintainers)_|

doc/user/admin_area/settings/visibility_and_access_controls.md

@@ -21,10 +21,7 @@ To access the visibility and access control options:
 
 With this option, you can define [branch protections](../../project/protected_branches.md)
 to apply to every repository's [default branch](../../project/repository/branches/default.md).
-These protections specify the user roles with permission to:
-
-- Push to branches.
-- Delete branches.
+These protections specify the user roles with permission to push to default branches.
 
 This setting applies only to each repository's default branch. To protect other branches,
 you must configure [branch protection in the repository](../../project/protected_branches.md),
@@ -37,14 +34,14 @@ To change the default branch protection for the entire instance:
 1. On the left sidebar, select **Settings > General**.
 1. Expand the **Visibility and access controls** section.
 1. Select a **Default branch protection**:
-   - **Not protected** - Both developers and maintainers can push new commits,
-     force push, or delete the branch.
+   - **Not protected** - Both developers and maintainers can push new commits
+     and force push.
    - **Protected against pushes** - Developers cannot push new commits, but are
      allowed to accept merge requests to the branch. Maintainers can push to the branch.
    - **Partially protected** - Both developers and maintainers can push new commits,
-     but cannot force push or delete the branch.
+     but cannot force push.
    - **Fully protected** - Developers cannot push new commits, but maintainers can.
-     No one can force push or delete the branch.
+     No one can force push.
 1. To allow group owners to override the instance's default branch protection, select
    [**Allow owners to manage default branch protection per group**](#prevent-overrides-of-default-branch-protection).
 1. Select **Save changes**.

doc/user/project/repository/branches/default.md

@@ -11,8 +11,9 @@ When you create a new [project](../../index.md), GitLab creates a default branch
 in the repository. A default branch has special configuration options not shared
 by other branches:
 
+- It cannot be deleted.
 - It's [initially protected](../../protected_branches.md#protected-branches) against
-  accidental deletion and forced pushes.
+  forced pushes.
 - When a merge request uses an
   [issue closing pattern](../../issues/managing_issues.md#closing-issues-automatically)
   to close an issue, the work is merged into this branch.
@@ -97,7 +98,7 @@ Ensure they understand the scope of this change includes references to the old
 branch name in related code and scripts.
 
 When changing the default branch name for an existing repository, you should preserve
-the history of your default branch by renaming it, instead of deleting it. This example
+the history of your default branch by renaming it, instead of creating a new branch. This example
 renames a Git repository's (`example`) default branch.
 
 1. On your local command line, navigate to your `example` repository, and ensure

lib/gitlab/access.rb

@@ -75,10 +75,10 @@ module Gitlab
 
       def protection_options
         {
-          "Not protected: Both developers and maintainers can push new commits, force push, or delete the branch." => PROTECTION_NONE,
+          "Not protected: Both developers and maintainers can push new commits and force push." => PROTECTION_NONE,
           "Protected against pushes: Developers cannot push new commits, but are allowed to accept merge requests to the branch. Maintainers can push to the branch." => PROTECTION_DEV_CAN_MERGE,
-          "Partially protected: Both developers and maintainers can push new commits, but cannot force push or delete the branch." => PROTECTION_DEV_CAN_PUSH,
-          "Fully protected: Developers cannot push new commits, but maintainers can. No-one can force push or delete the branch." => PROTECTION_FULL
+          "Partially protected: Both developers and maintainers can push new commits, but cannot force push." => PROTECTION_DEV_CAN_PUSH,
+          "Fully protected: Developers cannot push new commits, but maintainers can. No one can force push." => PROTECTION_FULL
         }
       end