For subscriptions started via Google Play, you should send your refund request directly to them. Please, bear in mind that refunds should be requested within the first 48 hours since the payment went through.
In case you got charged by iTunes, we can`t handle your subscription. All payments in iOS are handled by Apple iTunes, you should directly send your refund request to Apple Support:https://support.apple.com/en-us/HT204084
If you're willing to request a refund for subscriptions started via PayPal or Stripe (credit card), please submit a request