Hi
To view and manage your current subscriptions - and to turn off Automatic Renewal for the app - follow the instructions here:
View, change, or cancel your subscriptions - Apple Support
Once Automatic Renewal has been turned off, the subscription will end at the end of the current subscription period.
To ask Apple if you can cancel a previously paid subscription fee and receive a refund for a sum that you did not intend to pay:
- Go the following page: Report a Problem
- Click on the Invoices tab / tap on the Menu icon and select Invoices.
- View the invoice for your app subscription.
- Click / tap on Report a Problem.