In the Parent Dashboard, click the Account Details button.
Scroll down to the Children Details tab, Click Manage Subscription button next to the subscription that you wish to cancel.
Click the Cancel Subscription button.
Click Yes, proceed to cancellation.
Note: You can still use your subscription till the expiry date.
Cancel my subscription - Apple
If you subscribed to Matific via Apple, you must cancel your subscription via Apple.
Scroll down to Children Details > Click Cancel Subscription next to the subscription that you wish to cancel.
This will redirect you to Apple, from where you can cancel your subscription.