How do I leave a project?

I’ve been added in multiple projects. To be more precise, 16 projects. Most of them are inactive. And I simply can’t find a way to leave those projects!

I’ve read the docs and I’ve searched around here, without success. Can anyone please tell me what should I do in order to leave an inactive project I’ve been added to?

PS: contacting the owner won’t help, as some of them really won’t bother to remove me from the board.

Thank you!