I think you can't log out from the game currently, but there are a few ways to do so
If you're playing in web, i think clearing your cookies is enough
If you're playing from the downloaded version and you're in windows like me, type %appdata% at the File Explorer's address, open the Godot folder and try delete the folder called "Cuarantena" (Quarantine but in Spanish)
Anyways don't forget your password or else you won't be able to login lol (but some moderators can help recover your account if you want)