Here is the real way to UNINSTALL Copilot. I found this completely by accident by entering the app's settings:
Go to edge://apps/details/copilot.microsoft.com/
At the very bottom of the info splash page is an uninstall button. This will take you to the app settings in Windows. Apparently, it's installed via the Microsoft Store. You might be able to just go to the store and search for it there and maybe uninstall from there too, I'm not sure.
Once at the app settings screen, scroll all the way to the bottom and click uninstall again. Confirm that you want to uninstall.
Boom, gone.
Again, it's just an app installed via the Store, so finding it there should help get rid of it.
(I should note that I have Windows 10, I don't know if it's the same on Windows 11)
You could also just go to Apps and Features in the Settings menu and find Copilot there.