Hi Bob
I don't believe you can as the changes may be due to SU24 changes brought in by Step 2A and Step 2B
There is no magic button (that I'm aware off) for PFCG "undo". You can either look at change documents for the role to see what was done or if you want to mass fix your sandpits roles and not treat this as a testing/prototyping exercise then download the the roles from DEV and upload.
Regards
Colleen