My Aunt want's my uncle's name as co-signer be removed in the finance for the car.?

My Aunt bought a new car 2 years ago. Her husband was new in the country and had no credit at all and he wanted to establish his credit, so he asked for his wife (my aunt) to let him have his name as co-signer on the car fincancing stating that he would make half of the payments. She let him do so , and bought the car. 2 years later my uncle never paid a single cent but he is the one who uses it all the time. My aunt lives at her job and does not use the car, so the car is at the house where her husband lives. They are not divorced yet, bcoz she doesnt want half of all her ets be available to him for the taking until she gets a good case to fight with an attourney. she does not use the car and pays for all the bills, but he forced her to pay for his accidents. she payed because she doesnt want bad credit. how can she remove him as cosigner for the car before she finish payin? they live in NJ and he does not want to remove his name unless the car is sold and he gets half of the price