If you’re concerned about particular comments or posts linking your Reddit account to your real-world identity, and you know have a pretty good idea what those are, can you just delete or modify those?
I think that there are some other issues here, though.
That will help if you’re worried about someone doxxing an account via just casually doing Web searches, maybe.
But people have already archived copies of Reddit’s comment and post history. So if you’re worried about someone likely to be digging through such a database, this won’t help.
And I have no idea whether Reddit actually purges deleted comments internally, or whether they or any partners or future purchasers might have access to deleted text. I haven’t looked at their privacy policy, so I don’t know what they do.