How to cancel App Subscription?

recently I downloaded cam scanner from App Store in my phone but I didn't activate premium subscription and I think its activated by it self!!!!!!

I didn't use this app and now they want to charge me around 60 euro for one year and they don't let me to delete this subscription

I just wanted kindly to ask you cancel this subscription on my Apple Pay !!!

best regards

[Re-Titled by Moderator]