To Github's credit, they have been showing a banner consistently.
To my discredit - I never bothered to read that banner until I saw this HN headline
And Copilot is integrated with IDEs. Doesn't need any interaction with the github site beyond the initial sign in...
Sure, you can poke around in the settings and find one that you believe opts you out, but in lieu of clear and explicit instructions from GitHub, you'll have no way to find out. Only the possibility of finding out later that you guessed wrong.
You might have closed it...
Just go to your account settings and find the opt-out option.
$ git pull
$ vim foo.rs
$ git commit
$ git push
The chip on your shoulder doesn't make for productive conversation here.