How to remove my partner's name off a car title?

If his name is on the title, he (shared) owns the car. You cannot one-sided remove him from that, he needs to agree.

If he agrees, you both together (current owners) can sell the car to you alone (future owner), and you get a new title with only you. There is probably a short-cut to that, like a quit-deed, but certainly not without his agreement (or a court order).

You can always march down to the finance company, hand them a check, and boom the car is paid off as far as the finance company is concerned. That may have already happened. Until it does, the finance company has a lien on the car.

Now, the government also has a lien on the car. There are many ways to sell a car; some of them are managed by competent financiers who know how to settle liens on the car, because they buy cars that still have loans. Of course those people give you less money than a private sale on Craiglist. Suppose the car sells for $3000 and the liens are $1000. That means you get a check for $2000 instead of $3000. This will happen automagically if you trade-in the car on a newer car, but as said, you get less and pay more than a private sale. The dealer will do whatever it takes to get you out of that car and put you in another car in a way that's compatible with your cash flow, and he charges you for that indirectly.

You will need his consent to sell the car because you are two unaffiliated people who bought a car together. Unfortunately, you didn't go from "married" to "divorced", so the usual legal protections will not operate here. Don't do it again!

You could go to a finance company or credit union to get a loan with the car as collateral to pay off the government lien and the abandon fees and to replace that with a new finance company loan with the car (or some other asset) as collateral, or could simply borrow money to pay off the government lien and the abandon fees.

You could sue your partner for the money you had to spend to pay off those fees, but someone in prison probably isn't good for it. You could also sell the car to a third-party with the partner's consent, pay off the lien and the abandon fee with the proceeds, and get your partner to consent to deduct the lien payoff and abandon fees from your partner's share of the proceeds.

Of course, this only works if the car is worth significantly more than the amounts encumbering it, and if someone is willing to buy a car that is currently impounded.

If you can't afford to pay a $500 abandon fee, realistically, you also can't afford to hire a lawyer, or even to pay the filing fee to bring a court case, so you might very well end up being screwed.