In NJ all registered vehicles MUST have insurance, so, you need to turn in your plates if you do not want to have insurance on the vehicle. Also, in most cities in NJ, you CANNOT have a vehicle without plates parked so that it is visible from the street. So, it would have to be kept in the garage or behind your house.
So, every time you need to use the car, you will have to reregister, then call you insurance to add the car to your policy, then when you are done, you need to turn in the plates, show the surrendered plate receipt to your insurance agent & then delete the car from the insurance again.

Your registration will be suspended when the insurance co. reports the cessation of coverage on that vehicle to MVC. Also, some towns in NJ have ordinances about parking a car without insurance even if it’s in your own driveway.

In New Jersey, anything’s possible with these idiots.