Developers are unable to cancel Apple iTunes subscriptions.
This official article from Apple will help you cancel your subscription through your Apple ID.
Note: You might be logged into a different Apple ID than the one you used to subscribe to. Make sure you're using the same Apple ID and go through the steps in the article again.
If you subscribed on the website or in our Android app, please use this article to cancel.
Tags: ios, ipad, iphone, cancel, subscription, discontinue, free, trial, official article