How to remove remote management from iPhone 11

Hi, I’ve recently left my employer who allowed me to hand back my iPhone 15 in return for giving my an iPhone 11 to keep.

They have provided screenshots showing the phone has been removed from MDM and ABM but no matter what I try, I can’t get past the remote management screen on startup.

IT team at old employer says they’ve done all they can.

Is there something I need to do on the phone so I can use it?

Thank you