If he forgot the Apple ID (iCloud) password, enter the Apple (iCloud) ID, and click Forgot Password. See if he can get a Rescue or Notification email option if necessary. Link to contact Apple Support at the end of the 2nd article.
Apple ID - Manage -
Apple ID – Forgot Password *
If he can recover the password and sign un.
Purchases - View, change, or cancel your subscriptions. *
Purchases - Subscriptions not billed through Apple *
Link to contact Apple Support at the end of the article.
Purchases - the subscription that you want to cancel is not listed *
If necessary, contact iTunes Support for assistance. See the Apple Support articles below for contact information.
iTunes Support – world wide -
Apple Support schedule phone call -
Billings and Subscriptions -
If necessary, try Twitter
https://twitter.com/AppleSupport. -