AFAIK, you can't delete threads only move them, only mods can delete threads. If you look at a user's profile you can see all threads and where they would have been moved to. Neither of them have threads in any other place.
He reports his threads and somehow got these deleted very fast.
Check this thread which I archived -
https://archive.is/kOZ70 (its not self-moderated)
He gets his thread deleted and creates new self-moderated thread -
https://bitcointalk.org/index.php?topic=5288433.msg55568014#msg55568014