Disqus pushed out a tweet about 28 minutes ago explaining that forum deletions have been re enabled.
If you remember previously users who wanted to delete their sites from Disqus couldn't do so due to some upgrades (from my understanding). You can now delete a site if you desire by going to the admin panel >> settings >> advanced. The delete button is at the bottom of the page and deletions are permanent and cannot be undone.
Also, Disqus has updated Disqus 2012 with new changes.