I replicated the problem. It affects only the deletion of topics, and not of replies; thank you for your report. I would also suggest posting it in the following topic, for organization's sake:

http://www.jazz2online.com/jcf/showthread.php?t=9638

Your problem probably has to do with the upgrade, and seems to affect all accounts that I have tested so far. You may also want to contact FQuist via Private Message, or perhaps Bob, so they may assist you, as it seems this is more of a MySQL-level problem.

Until then, I suggest asking administrators to delete the threads for you, as they seem to be unaffected by this bug.

~ Traft