Auditing and blocking the access apps have
When considering if an app should continue to have access to certain types of your data or hardware, ask yourself if you use features in that app that requires such access? If you never check yourself into places in Facebook, why should the Facebook app continue to have access to your location data (which can be used for tracking your movements)?
Go to Settings -> Privacy
You will see a list of types of data, from location data to photos and items like camera and microphone.
Tapping on an item takes you to a list of apps that have access to that type of data.
To restrict an app from accessing that data, toggle its switch to off.