"I want to remove a vehicle Ive added by mistake"

Hi fusionphotograph,

Currently, the ability to remove a vehicle in QuickBooks Self Employed (QBSE) is unavailable. You'll want to edit the information to change it to the correct one.

Here's how: 

1. Click the Gear icon on the upper menu.
2. Select Vehicle info.
3. Change it to the correct information.
4. Click Save.

Please check this article for more information about automatic mileage: Use Automatic Mileage Tracking for QuickBooks Self-Employed.

For future reference, you can check this article: QuickBooks Self-Employed Overview.

Keep me posted if you have further questions about QBSE. I'm always around to help.