If you wish to keep the vehicle as a business asset for a future sale, simply report zero business miles this year. No depreciation will be recorded.
If you check the box for "I stopped using this vehicle for business" at the bottom of the page titled "Let's verify the make and model for your business vehicle," TurboTax will "write-off" the vehicle as if it had been sold. This will trigger depreciation recapture, if applicable. You would not be able to report a sale for this vehicle in the future.