A staff member (admin/moderator) has the delete topic function in the topic admin wrench, though the topic wouldn’t actually be permanently deleted, just hidden from public view. If you’re not an admin/moderator, you could flag the topic and request this kind of deletion?
There is a ‘permanently delete’ option in a site setting, but this has to be enabled from the command line (or by request to the hosting provider, depending on the set up), so isn’t necessarily available to every forum:
You can also delete records from the rails console, but this would also need server access.
So, I suppose the answer is: ‘yes, but it depends on your level of access’