You can delete an existing mileage on the Earnings page.
Here are the instructions:
See the Earnings page by tapping on the bottom right button on the lower menu. This button is called Earnings.
Now that you are on the Earnings page you can delete mileage manually by finding the earnings entry within the Weekly cards.
Tap on This Week
Scroll down to the right date
Select the date for the mileage you wish to edit
- Tap on the Mileage row at the top
Tap on the red colored Delete button
Confirm your Deletion request
An alert will drop down from the top menu to let you know that your mileage deletion was saved.