These instructions will help you cancel your Google Play subscription. Any billing questions or inquiries about your Apple subscription should be directed to Google Play support.
If you would like to change your subscription from a Google Play subscription to a SYSTM web subscription, you will need to cancel your Google Play subscription and wait for it to completely expire before starting the new subscription. See Creating a SYSTM subscription (web, Mac, Windows).
Open the Google Play store and click on your photo avatar in the top right corner to manage your apps, settings and subscriptions.
Select Payment and Subscriptions
And then Subscriptions. You can view, manage and cancel your subscriptions here.