I never knew I had such... power.
Don't know about locking, but I definitely remember someone saying on this board that the entire thread can be deleted by its author. Though maybe it's a feature of an old site, just like "ignore" button (Mr. Doe & drbeachboy told about having it back in the day). Anyway, my point is if you're able to lock your own thread, then obviously you're not the only 1 who has such "power". Just being a realist.