How do I cancel my membership?

1. Open the Settings app on your device.

2. Tap your name.

3. Select 'Subscriptions'. If you don't see this, tap 'iTunes & App Store', then tap your Apple ID, tap 'View Apple ID', sign in, scroll down and tap 'Subscriptions'.

4. Tap your Supporting Membership subscription

5. Tap 'Cancel Subscription'.

If you no longer have access to your iOS device anymore, you can cancel your subscription on a different device. Read more in this article from Apple  

To cancel your Supporting Membership on Android

1. Open the Google Play Store on your device,

2. Click the three horizontal lines in top left corner (Menu), then choose 'Subscriptions', 

3. Select your Supporting Membership subscription.

4. Tap 'Cancel Subscription'.

If you no longer have access to your Android device anymore, you can cancel your subscription on a different device. Read more in this article from Google.