iPhone or iPad allows you to customize the settings of the location services for individual applications.
However, it often makes sense to activate or deactivate all location data at once. How this works is explained here.
How to turn GPS and location services on and off for iPhone and iPad
First open the iOS settings from your home screen
Tap on "Privacy" in the settings
Continue navigating to "Location services"
To activate all the location services, move the slider to active in "Location services". (Move to the left to deactivate)
You now know how to completely deactivate or activate the location services on the iPhone or iPad.