The easiest thing to do is to delete the vehicle. Follow these steps and screenshots:
1. Sign into your TurboTax account
2. Select Federal Taxes (Business in the Home & Business edition).
In Online TurboTax Premier, click the bars at the upper left corner to show Federal Taxes on the selection list; enlarge the screen if needed to show the left side selection list. If you don't see the menu bars, you must first step through each of the interview screens in TurboTax.
3. Select Business Income and Expenses and in the next screen, click I'll choose what I work on.
4. On the Your Income Summary screen (TurboTax Premier edition) or the Your Business Income screen (TurboTax Home & Business edition), scroll down to the Rentals and Royalties group.
5. Click Start/Update next to the Rentals and Royalties line and step through the rental interviews to the Your <name> Rental Summary screen.
6. On "Rental and Royalty Summary" screen click Edit/Update to right of Vehicle Expenses (See the attached screenshot below. Click to enlarge.)
7. You should see the vehicle you wish to remove and you can choose to Delete it. (See the attached screenshot below. Click to enlarge.)