One. Remove all personal information you feel necessary.
Two, change your name in the official thread.
Three, change your email to something that doesn't exist.
Four, change your password, you won't receive it due to the new non-existent email, and your account shall die in peace. Never to be revived.
iirc that's how the game works.
I'm sorry to hear you wish to leave, though, see you on MSN.