Again, I'm not familiar with the specific situation. A user can deactivate an account. It's in your account settings. We have a process for account deletion to happen soon after. There's a 30-day grace period during which your account is deactivated. It's removed from the service as of the time you deactivate it. Then it's deleted. The process for deleting starts happening 30 days later.
On December 6th, 2012. See this statement in context.