As long as you didn't enter any information for box 20 details, including zeros, in the follow up questions, this won't cause any problems and should not change your return in any way.
If you did enter some information and you need to get rid of it, here is how:
I tried to delete box 20 info per your instructions above but it won't allow me to delete
I did input info that I need to delete in box 20 but it won't let me delete
Did you uncheck the Box, then continue and <blank> the entry from the Box 20 drop-down box?
I'm having the exact same problem. I've tried all above to get rid of or adjust box 20 info and all related boxes thereafter.
Hoping for further follow up
Actually, I just got it to work so your solution was helpful. Thank you