I was promoted to (assistant) GM in a game a few years ago. I cannot find a way to leave the game. The current workaround is to contact the original GM and ask him to remove me. I would rather not contact him for personal reasons. So I'm left with looking at the game (clutter) on my list (which is a mild irritation, but an irritation nonetheless). Players can choose to leave games. I think players who were promoted to GMs should be able to leave of their own accord too! This is especially true for promoted GMs who are not the original creator of the game.