Hi,
I'm also having this problem. I had 6months Gamepass which expired around Dec 23. I can't remove BT/EE management of my account, I had originally ticked this do not auto renew and now I'm unable find the content partner section in my account. The knock on effect is, as BT/EE is set as the manager for my xbox account I am unable to extend my Gamepass through Microsoft. I will also mention I have have been on to BT multiple times for this problem and it seems BT call centre staff are unaware that they provide Gamepass as a service. This is very frustrating and any help would be very appreciated.