How to turn off the GPS

I am pretty new to Garmin Instinct, it has been only a few months.  I know how to turn on the GPS, you just hold the GPS button, and it shows you your GPS coordinates.  I do not know how to turn off the GPS function, however.  I press the BACK button, and the normal clock face appears.  Is the GPS on when the clock face appears, or do I have to manually turn off the GPS? somehow?