How do I return plates and unregister my car

You can cancel your registration online at Mass.Gov/RMV. Once you cancel your registration, your car/truck cannot be driven on any public way in the Commonwealth of Massachusetts. When your registration is canceled, the RMV will provide you with a registration cancellation receipt. Once your registration is canceled, you must recycle or destroy your license plates. Plates can be cut in half and discarded; or you can recycle destroyed plates if your town accepts them at the local recycle center.

I think you can cancel on line print a receipt and dispose of the plates they told me to do what I wanted with them