Follow these steps to turn off your auto renewal on your iPhone:
- Launch the Settings app on your iPhone.
- Tap on your Apple ID at the top of the screen.
- Locate Subscriptions
- Tap the name of the subscription that you want to modify.
- Click "Cancel Subscription" and click confirm
- You should receive a pop up that will confirm when your subscription will expire.
If you would like further information or assistance, please contact Apple directly at: https://support.apple.com/billing.