By photo tagging, do you mean GPS coordinates? Isn't that done by the app that takes the picture?
On Facebook and many other social apps you can manually specify the location a photograph was taken. Some apps will ask you for the location if it's not available from the operating system or metadata.
Can't I disable Wi-Fi?
Sure. Go nuts. But you have to connect to the internet somehow to use the app, so if you're not on wifi, it can get your location from your cellular network.