You don't clarify if this vehicle is a SCH C asset, SCH E asset or SCH F asset. But basically;
Work through the vehicle is the vehicle asset section and select the option for "I stopped using this vehicle in 2021", then continue on. The program will ask you for pertinent information after that, as it will matter why you removed it from use. (personal use? You sold it? Vehicle was totaled in an accident? Something else?)