There's been a request going for several years now to disable Pull Requests on G...

There's been a request going for several years now to disable Pull Requests on GitHub[0]. They allow project maintainers to disable Issues, they should also be allowed to disable PRs rather than use automation to close any opened PR. Other SCM products (e.g. GitLab) offer the ability to make PRs available only to project members, or disable them completely.

[0] https://github.com/dear-github/dear-github/issues/84