On the Options screen there is a Subscription button where you can view and manage your subscription.
 
Or, you can navigate to your active subscriptions under your Apple ID and cancel it there. Follow these instructions to cancel the subscription:
  1. Open the Settings app.
  2. Tap your name.
  3. Tap Subscriptions.
  4. Tap the Spirit Island subscription. Don't see the subscription that you're looking for?
  5. Tap Cancel Subscription. If you don’t see Cancel, the subscription is already canceled and won't renew.