Whatever you do with their property, do it in a manner that will hold up in court. If they are sorry enough to leave it on your property, if they get a chance they'll sue you for every penny they can get. You could also face criminal charges if their property is removed without the proper...
I've always thought the "no fighting back" rules are part of the cause of some school shootings. You can't expect someone to tolerate a bully, period. Kids don't have the coping skills of most adults and after taking as much as they can, they explode.
http://missingchildrensnews.blogspot.com/2013/07/walhalla-fair-play-south-carolina.html
These children were possibly seen in Rome, Ga. on 7/9/13. If you see them call your local 911.