Noob (me) made a mistake installing - would appreciate help to correct

I apparently made an incorrect selection when installing Python 3.7 and now every time my MacBook (OS 10.15.7) starts, the IDLE opens and I get this error:

File /System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/test_int.pyo Failed to Decode

I have tried uninstalling by deleting from Applications and deleting the /Library/Frameworks/Python.framework folder but no joy. Each time I reinstall using the universal installer I get the same error. I obviously don’t know what I am doing and would appreciate guidance to where I might find directions to correct my error.

Thank you for your time.