I do not think there is a way to remove or terminated self moderation from a thread you created to be self moderated, if there was, I believe the information would have been circulated well enough that most active forum users would have come across it and learn how to do it..
I don't think there's a way to change it, but I will definitely look into it.
Actually, there is a way to change it. I was certain I have read somwhere it was possible and how to do it. So, I tested it yesterday after posting my previous comment and it worked.
What you need to do is to move the self-moderated topic to the
Meta board then move it back here.
Topics on Meta can’t be self-moderated. So, when you move this topic there, self moderation will be removed automatically.