Theia has a member warning system, which allows those you specify to give members warnings, and upon receiving a specified number of warnings, the member's account will be either locked or deleted.

Configure the warning system

The first thing you need to do is specify how many warnings a member must receive before some action is taken. For this, load up the "tools" page and look under "system configuration" for a tool reading "configure warning system" (admin tool 009)

There are only two fields here, and the first, # of warnings before automatic action, handles what we just talked about; how many warnings are necessary before some action is taken.

The second field, what to do, is used to specify what action you want to be performed on the member when they receive the required number of warnings. They can either be automatically deleted, or automatically locked. For safety sake, it's suggested just to have the accounts locked, but how you run your site is up to you. ;)