Be logged in, then use the deletion link. Good work!
For paying members however, it is somewhat more complex, unfortunately. From their FAQ: Please delete ALL info from your profile, cancel your VIP in your profile settings and email www.fubar.com/support and request to be deleted. If you are a VIP, we must wait until your VIP runs out. We do this to ensure that no one compromises your account and tries to delete it. If you are emailing support, make sure you send the URL to your profile.