Generally, you can't affect steps that have been automatically counted by the device.
If they're showing up on the graph for the day, about all you can do is log a 'Driving' activity for the appropriate period of time which should remove the steps if it's done correctly. The compromise there, however, is it will give you a flat calorie burn of double your BMR rate for that period.
Mike | London, UK
Blaze, Surge, Charge 2, Charge, Flex 2 - iPad Air 2, Nokia Lumia 925 (Deceased), iPhone 6
Take a look at the Fitbit help site for further assistance and information.
