I reversed the RMD contribution and rolled it back to the same account. Turbo tell me it is not permitted and I owe a penalty. What Have I done wrong?

You probably said you took the RMD.    There was no RMD so you must answer that "None of this distribution was a RMD" or "RMD not required", depending on the question, then yiu will get the screen to rollover.

Repeating the interview will not work - delete the 1099-R and re-enter to reset everything.

I tried deleting the 1099-R and reentering with no RMD boxs checked.  This did not solve the problem.

The only way i solved the problem was to delete all entries and start over from scratch.  

I entered the 1099-R entries and answered all question exactly the same way there were before total deletion.

That worked.  There is a program or system error in the 2020 version of TurboTax that required this extreme action.  Of course, my original error in saying that part of 1 1099-R was RMD, but that was MANY iterations    ago.Just glad I found a way.

Thanks to all who helped.