Disable Post Locking

Skildring

Disables automatic post locking so multiple users can open the same post in
the administration panel.

Warning: Post locking was an addition to WordPress in order to prevent such
bugs as overwritten autosaves (coming from multiple authors), and of course
to prevent accidentally overwriting another user’s changes with older content.
These are often never problems for many users, and you should likely be
communicating with your fellow editors when making changes anyway. This plugin
makes the choice of relying on the latter rather than post locking, so you
may run into those problems again.