Comment Do not transfer = Cancel (Score 5, Informative) 78
I suppose the poster didn't actually RTFA as you can either accept by clicking, accept by doing nothing or not accept by cancelling the account.
What if I don’t want Opera to take over my account?
Go to http://www.fastmail.fm/ login to your account, then go to the Options -> Cancel Account screen and enter your password to confirm you want to cancel your account.