View, change, or cancel your subscriptions - https://support.apple.com/HT202039 - Learn how to view your subscriptions that renew automatically, change your subscription period, and turn off Automatic Renewal." "If you don’t cancel more than 24 hours before your renewal date, your subscription might renew." Deleting an app does not cancel a subscription. Stopping the auto-renewal of a subscription only does that, it does not immediately stop the subscription, nor result in any refund.
If you want to try to request a refund for a subscription, contact:
iTunes [Store] Support - Use this form for assistance with account and billing, code redemption, or purchase questions --> https://www.apple.com/emea/support/itunes/contact.html
or
Worldwide iTunes support --> https://support.apple.com/country-selector/itunes