I e-mailed them, then waited a few months, then e-mailed them again, then went through the site manually blanking my answers then deleting them (surprise, the 'delete' button just hides your answer), and only then did I get an e-mail back saying my account had been deleted.

I agree with nileshtrivedi these Quora guys seem like assholes - that's why I decided to delete my account in the first place.