I can't remove a device from my Apple ID

I tried to remove my iphone 11 from my apple id, but I am receiving the following message, “iPhone could not be removed because of an error. Try again later. I, then signed out with the iphone 11, but still not able to remove it. I will give it back to it department for someone else’s use, and I do not want to encounter any unwanted interference in future. Can someone help me removing for good?

[Re-Titled by Moderator]