How to delete a "lost" Discussion List?

When I first got my DH account, a little over a year ago, I set up a discussion list, just to try it out. Just recently, I experimented by creating a second list, to check out the interface again.

Now I see the original list doesn’t show up in the Discussion Lists tab of the control panel, but I can find its admin interface by going to

I have deleted the second list (my curiousity is done), but I can’t figure out how to delete the first one, because it doesn’t show up in the control panel.

I want to get rid of this thing, or at least completely disable it so that it can’t be used. Any ideas? There doesn’t seem to be a “delete” option in the MailMain interface.