For accounts created through in-app purchase on an Android device, you can manage the billing of your subscription through your Google Play Account.
Google provides instructions on how to manage subscriptions in your Google Play account here: Subscribe to services or content
Google provides instructions on how to manage payment methods for your Google Play account here: Add, remove, or edit your payment method
Google provides instructions on how to cancel subscriptions here: Cancel, pause, or change a subscription on Google Play
Note: If you turn off auto-renewal for a subscription, you'll continue to have access until your current subscription period expires.
For any sort of refund through Google Play, you can follow the steps listed here: Request a refund for a Google Play purchase