Cannot delete group in contact
I've been using Contacts for... forever. I have really old groups that I'd like to delete. I tried selecting the group and deleting it (Delete groups and Smart Groups in Contacts on Mac - Apple Support). I tried deleting a contact from the group hoping an empty group would go away, but when I tried to delete the contact in the group, it deleted the contact globally, and the group remained. I thought perhaps it might be an odd smart group, though the group members had nothing in common, no extra fields, nothing. I deleted everything from ~Library/Application Support (Can't Edit or Delete Group in Contacts Hi… - Apple Community). It deleted all of my contacts which were thankfully restored from iCloud, but the annoying groups remained. I thought perhaps this was because the advice was for High Sierra.
I don't want to hide the sidebar as I'd like to create a few smart groups. But these old ones are annoying. They don't appear to be smart groups as I can't edit them or see any criteria to change.
How can I delete really, really old groups from Contacts in Monterey (12.3.1)? I also have an iPhone and iPad but in my experience they are harder to delete things like groups. I logged into iCloud but it doesn't show any groups.
Help! and Thanks -
MacBook Air 13″, macOS 10.15