A factory reset only deletes the /data and /cache partitions - the /system partition is not affected, so the beta operating system will boot up. You will have lost all user data, however, and will have to log into your accounts again, install apps, etc.
Ok, so request to leave beta, back up again to PC, then factory reset? How do I go back to original UI? I'm passing the phone to someone else to use from now on.
