Removing the base powers on the sections. Mods give / take all powers.
So, on the Admin page, whenever a user gets a certain amount of points, they get put on notice for a privilege. Those points would be like this, likely:
The Mods can approve or reject the ability.
The mods go here.
On the highlighted area, there is a link that says "Remove" and when clicked, it removes the privilege. Also an "Undo" button.
A follow up from this, add "Chatting" as a privilege. No matter what points you have, you have it. Unless the Mods take it away, then you cannot enter chat.