I think OL Mods should have a button to sign out of projects themselves. This would then notify the CM of Mods decision. It would also be great for the Mod to have the possibility to write a text with the reasons why they’re quitting the project. But once you click that button, you would immediately remove yourself from the team.
This would solve issues we face when being assigned to old projects where CMs are no longer active. Not to mention that it would greatly speed things up and save everybody lots of hassle.