As far as this forum is concerned, Imo I would have suggested that the admin can also ensure that scam project are not allowed to advertise here but I think I have also seen some bounty threads being tagged as warning for participants (or maybe they should just remove such thread entirely).
It's better not to remove the scam warning as that will alert and remind investors of the scam projects, even outside this forum. Once the threads are gone people who didn't read about it before it was gone will remain in the dark and fall prey.