How to manage my subscription when it's purchased with Apple Store?

If you would like to cancel a subscription purchased through the Apple Store, please follow the steps below:

1. Make sure you're signed in to the correct Apple ID account.
2. Go to Settings  >  Passwords & Accounts  >  Accounts  >  iCloud  >  Subscriptions.
3. Find DoFasting subscription, then tap Cancel subscription, and then Confirm.