Until recently, Facebook made it very difficult to delete accounts and users were only able to deactivate their accounts with ease. Now, by e-mailing Facebook directly, users can request their account be deleted.
It's so easy Bill Gates can do it! Well, Bill stopped using it, but his account has not been deleted. Apparently, he was getting around 8,000 friend requests a day and stumbled upon some creepy fan-sites.
Previously, he had been using the site for 30 minutes a day after Microsoft invested in the social networking site.
Sadly, it still isn't possible to just delete your Facebook account manually without a lot of effort.
NYTimes: Quitting Facebook Gets Easier

