How do you surrender a car to the bank or lender?

Bad idea!! This is called a voluntary repossession. Your credit will be ruined for 7 years, and you will still be responsible for the difference in what the bank sells the car for and the balance on the note. Go to the bank and sit down and work out new payments. Sell the car yourself and borrow the difference if you are upside-down on the loan. Have someone possibly take over the payments. Do whatever is necessary to avoid a repossession.