If by terminate you mean to remove from the forum maybe an admin could do it IF nobody else has added to the thread. With that you might ask "how about if I ask for permission from anybody/everybody who did add to the thread". I really don't know. I'm just going on the principle that it's only software so anything should be possible in theory. However in practice you (read admin) could be opening a big can of worms, and once admin do it for one person... Need I say more.
Again maybe an admin could do it for you. It's not possible for you to do. Also, again, it will probably depend on if anybody has added to the thread.
Sorry I couldn't be of more help. I doubt I've said anything that both of you didn't know already.