Thanks - I like the idea of tweaking the shared drive, but would prefer the cleanliness of actually removing the permissions. I also found that github article, but was hoping for a 'bulk' process.
Here is what I did:
I run this for every file and filter out the Inherited permissions (the shared drive permissions):
gam config csv_output_row_filter "permission.teamDrivePermissionDetails.0.inherited:boolean:False" user <me> print drivefileacls <fileID> oneitemperrow >> Permissions_comp.csv
Then run this:
gam csv Permissions_comp.csv gam user <me> delete drivefileacl ~id "id:~~
permission.id~~"
The duplicate header lines in the csv just throw a harmless error.
Not pretty, but it worked.
Thanks!