"Cannot remove" error during unsync

I’ve gotten an error trying to unsync a relatively large directory from my local workstation:

“Cannot remove completely because it has files that are still being sync’d or have matched an ignore rule. Please remove these files from the folder to continue unsyncing.”

There are no ignore rules. Does this mean I need to remove the files on the Google Drive side (via the web client)? Or if I delete them locally will it not delete the cloud version?

I can back up the files manually from the web interface then experiment, but they are owned by a coworker, in their GSuite account, so I would prefer not to mess this up and have to explain to them how I deleted their files.