If the vehicle is registered in your name I would keep it insured. Florida will suspend a license of the registered person if a vehicle isn't insured. If it is in his name, I would try to contact him to discuss options or at that point, you could drop him from your policy. You can get in trouble with your insurance company if they discover it's at a different address than the primary one listed on the policy.
If you have any other questions, don't hesitate to ask