How do I delete an unused admin from an iphone 13 where Armor has expired?

I have 2 listings for my iPhone 13 Pro Max on the device list. I am running an Orbi router RBR750 on a home network, firmware version V4.6.14.3, Originally I was also running Netgear Armor by Bitdefender. After speaking with Bitdefender reps, they advised that I didn't need both Bitdefender and Armor so I let Armor expire. When I try to delete the offline iPhone listing it denies my attempt to remove it, citing an error "Admin device cannot be block or unblock".. The iPhone is a 13 Pro Max running IOS 16.6 and I am running the Orbi app by Netgear version 2.29.0.123. What am I doing wrong?