Cancel Recurring Membership

This support article explains how to cancel a subscription from Apple ➔ If you want to cancel a subscription from Apple - Apple Support

Notes:

• You might need to scroll down to find the Cancel Subscription button. If you don’t see Cancel Subscription, then the subscription is already canceled and won't renew. An "Expires" date (instead of "Renews") means the current subscription will just run until then. "Resubscribe" is just in case you change your mind about having it end.

• Deleting an app does not cancel a subscription.

• If you don’t cancel trials more than 24 hours before your renewal date, your subscription might renew.

• If you don't have an Apple device, see the options near the bottom of the support document.

I do not work for Apple, I am just a regular user of Apple products like you.

If you son bought it under his ID, you will have to use his ID to cancel the purchase. Note there is a button in the document I provided that apparently lets you do this online. I suggest you thoroughly read the document because it talks about all kinds of options and things to do under different scenarios.