You can remove the car registration fees entered in TurboTax by following this "path":
Federal>>Deductions and Credits>>Cars and Other Things You Own>>Personal Property Taxes
Once in this section, find the box where the car registration fees are entered, and delete the entry in that box.
Another alternative to find this area is to click on the "magnifying glass Search" icon and enter "car registration" in the search window, hit return, and then click on the "Jump to car registration" link.