I believe he has that power.
It's true.
https://www.youtube.com/watch?v=-dJolYw8tnk
Most people are usually posting something that they thing is identifiable but really isn't (like "an Elder in our hall had an affair"), and they are posting anonymously anyway.
If someone has taken a comment from here and shared it elsewhere, there isn't a lot I can do about that, but if someone has genuinely posted something that could legitimately become a cause for regret, I can remove or change it.
But we don't do the "I'm leaving now, please delete ALL my posts" thing, as it is unfair to others who have taken part in a discussion.