Contact List Clean-up


I'm new to a company, and new to their sheets as well and in trying to clean up an older sheet of existing consultants, it has former consultants listed and they get populated in the weekly schedule occasionally. I can't seem to delete them because they're not in my personal contact list (screenshot of contacts I can't delete). Is there any way for me, as an admin, to delete them? Or is the sheet owner the only one allowed to do this?