In the middle of the page, you should see a line with "Self Employment Income/Expenses" and an "Edit" button
Click on the "Edit" button
Scroll down and you should see an "Expenses" section with a "Vehicle - XXXXXX" under it with an "Edit" button
Click on the "Edit" button and follow the prompts on the screen. Eventually you will get to a checkbox that says that vehicle is the only car you have for personal use
