there are a few websites out there with instructions on how to kill that by scrolling up and getting the Copilot chat window. I wish I could now remember them but I know that one of them points to an edge extension called Tamper Monkey and gives directions for a script that kills it and that is what I am using. I have also gone so far as to block the Bing website that Edge goes to when you click on any of the copilot icons so all that pops up for me is a blank page.
I hope this helps