At Admin Panel -> Settings -> Switches you have an option to enable a warnings system. The "warnings system" switch activates the ability to assign warning points while editing or deleting items. When a warning point is assigned, a private message (or email if private messaging is off) is sent to the member telling them that they've been warned and listing the reason which has been provided in the reason for edit or reason for deletion box.

You can keep track of who has the most warning points in the moderator control panel on the "Moderator Notes" tab. Use these warning points standings to decide when it's time to ban someone.