If you purchased a subscription via iTunes in one of our apps on an iPhone or iPad and would like a refund, you must contact Apple directly, as they do not provide us with the ability to process that for you. Only Apple Support can process refunds for purchases made through an iTunes account.
You can contact Apple Customer Support directly at https://getsupport.apple.com/. When you get to this page, click "Billing & Subscriptions" followed by "Subscriptions & Purchases." Once here, you'll be given a variety of avenues through which you can contact Apple.
We also recommend that you cancel your subscription to prevent being charged again next cycle. To do so, you'll just need to turn off auto-renew within your phone's iTunes account settings. We are not able to manage this for you on our end, but the steps are easy and you can do it at any time. Please see THIS support article for details