This article explains how to turn off Family Sharing for any device that supports it in iTunes. This includes devices running iOS 8 and later and macOS 10.10 Yosemite and later.

If you're the organizer, follow these steps in your device's Settings app to turn off Family Sharing for everyone:

Open the Settings app.

Select your name at the top of the screen, then choose Family Sharing. On iOS 10.2 or earlier, go to iCloud > Family.