There is no need to have insurance for either selling or buying a car. Just simple like this, without an insurance, nobody can drive that car. For buyers, they can't register the license plate for the car w/o insurance.
So, for you, you definitely don't want to renew that policy. After 9/13, you can still sell the car to anyone, but who may need to get insurance at first to test-drive the car, or buy it directly w/o test-drive