You've probably stumbled upon this researching how to remove the Xbox Game Bar. This gist includes a few different methods you can try. Please note that some of these first options are probably not be available unless you are running an older version of Windows 10.
Uninstalling/Removing the Game Bar (old Windows 10 build GUI options)
(this is no longer an option on any recent Windows 10 build)
- Press Windows Key or click on the Start menu.
- Start typing
Game Bar, until you get the Xbox Game Bar app to appear in the results.
- Right-click on the app and pick
Yesto the prompt, and wait for the process to finish.