You should contact your local Department of Motor Vehicles to find out if you need to keep this vehicle registered, insured and inspected. There is no general answer to the question since different states have different laws regarding inoperable vehicles.
For example, in Connecticut if you do not want to pay insurance on a car that is inoperable or being stored you must turn in your plates to the DMV and request that they be put on "hold." At that time, you may drop insurance coverage on the vehicle.
California has more strict guidelines for inoperable cars. California law requires vehicles to be currently registered if they are driven, towed, stored, parked on public roads or highways or parked in an off-street public parking facility at any time during the registration period.
If you have an inoperable vehicle in CA and it will not be in any of the places listed above, you can apply for non-operational status on the vehicle and pay a planned non-operation (PNO) fee. Once this status is placed on a vehicle's record, it remains until you decide to operate the vehicle and pay full registration renewal fees.
If in your state you are required to keep insurance on the vehicle, you might want to lower your deductibles or coverage to reduce your insurance rates.