I wonder why it's so. Sometimes one feels the need to delete a thread one started completely because of lack of interest in further discussion on the topic or one finds out that the issue raised in the OP isn't worth it any more and it becomes shameful that one even had such a thread to one's name. I know one can lock up the thread but what about in a situation where one isn't even proud that such a topic was started by one and needed not to be reminded of it again? For instance, if I lock up a thread I will still stumble onto it once in a while. But if I delete that thread that will be gone forever from my post history.
Only moderators can delete a thread even if it doesn't have anyone else's post on it. You have the option to report the thread you want to remove to a moderator just as you would report a spam post, if the moderator finds a clear reason then there is a chance your thread will be deleted. That's the only solution, or forget about that thread.
I once tried deleting a thread I created seconds after posting it as an experiment, it never worked. But it is possible to be removed if you report it to a moderator.
If mods can do that, why can't thread starters themselves? That's the area of my puzzlement.
I've asked that question before, but I don't know maybe it's part of the moderation of this forum for a long time that only moderators can do.