You can cancel the subscription anytime with the below procedure.
iOS
- Open the Settings app.
- Tap your name.
- Tap Subscriptions.
- Tap iSharing.
- Tap Cancel.
- Please click the link for the detail: Apple Customer Support
Android
- Play Store > menu(top left) > Subscriptions > iSharing > Cancel subscription
- Please click the link for the detail: Google Customer Support