What do i do if i can't get the other person to sign their name off the title of vehicle?

i live in virginia; i financed a car and added someone as a co-applicant on the loan and car to establish and build his credit. he paid for some of the down payment, and half of payment for a couple of months through a joint bank account. i have the car in possession, i have paid off the entire loan and he refuses to sign his name without getting money out of it. i have receipts of payment and letter of proof that i paid the loan off. do i owe him the money he has paid for down payment and a few months? or does he owe me half of the loan? what should i do to solve this issue and get his name off?