After doing an experiment, it seems that the most permissive permission wins:
If the User has Edit permission and the Group has View -> the user can still edit
If the User has View permission and the Group has Edit -> the user can still edit
(in is both in TeamDrive and PersonalDrive)
You can remove the shared files with you from "My Drive". Be careful to not remove them from folders shared with you as editor because you could remove files from the folder for all.
Does deleting a file from Incoming folder in Google Drive delete the original file?
What's an efficient way to delete shared Google Drive files?