It’s not done through our app; it’s controlled by the app store.
For iOS devices, you have to go to your phone’s Settings -> iTunes & App Stores -> select your Apple ID and tap “View Apple ID” -> Subscriptions. From there, you can see all the subscriptions that you have, and cancel the ones you don’t want.
For Google Play, you can manage all your subscriptions directly from your Google Play account. Tap on “Subscriptions” and cancel the ones you don’t want.