I currently have a vehicle that is financed and can't no longer afford. I would like to know what is the process I have to take to retrun the vehicle. Would it ruin my credit? Do I have to pay a penalty?

You would probably be better off either trying to sell it or getting someone to take over the payments. If you turn the car back in, you will only get credit for its book value. This will probably be less than the balance owed on the loan. You will still owe that balance.