You should only remove their tags if they are not banned by the admin by then, let them each to report a minimum of 200 garbage posts with an accuracy higher than %80 and then remove their tags. we'll keep an eye on them after that, if they keep doing the same thing, you could tag them again.

Other people could think:
You could be tagging these people to have a market for your own farmed accounts. it would make it easier for you to sell your clean accounts if these garbage posters are red tagged.

Having them to help the forum by reporting could benefit only the forum. leaving the decision to you could benefit the forum, however you could make it to benefit yourself more than the forum.

My tongue likes no English. sir TP.