I accidentally selected yes to if I paid a car registration fee and it won't let me undo it, what should I do?

Use the little trash can icon to remove it.  To enter (or delete) your personal property tax, do this:

1. Open your return, if you're not already in it.
2. Search inside your program for personal property taxes (use this exact phrase) and then select the Jump to link at the top of your search results.
3. Answer Yes to Did you pay personal property taxes in 2020?
4. Find the car registration fees and delete them.