Transfer: Menu--Account--Transfer Account--OK--when the other device successfully accept transfer, tap Complete
Accept: Menu--Account--Accept Transfer--Input Transfer Code--Complete
If you tap Transfer Account but do not input the code on any other device, your account on the original device will not be affected. But if sometime after you want to transfer it, you have to go through the transfer process again to get a new code, for the Transfer Code will be reset after you leave the Transfer Account screen.
iOS 7 user: deleting the app may also delete your account
*This process is not reversible.