How do I permanently leave a room?

You can only leave a room if you are not the owner of the room. Leaving a room means that it will no longer appear in your contact list, so you will not be able to access it again in the future, but the room will not be deleted and other users will be able to continue to collaborate. To leave a room you have to access it, and then you can click on the drop-down next to the room name at the top of the screen. In the configuration screen you can leave it by clicking Leave this group.