Ok so you have managed to start a subscription but can’t figure how to turn it off? No wonder, they have made it very hard indeed to stop subscribing to services. But once you know how it’s quite easy:
Go to Settings on your device (iPhone, Ipad)
Find iTunes & App Store
Tap your Apple ID: email address
Choose View Apple ID and enter password
Find and tap on Subscriptions
Find the subscription you want to edit and turn off the auto renewal option.