You must first cancel any subscription automatic renewal (if you simply delete an app this does not cancel subscriptions):
Review the information in this support article by clicking on the link:
See or cancel your subscriptions [subscription automatic renewal] - https://support.apple.com/HT202039
- "If you signed up for a free or discounted trial subscription and you don't want to renew it, cancel it at least 24 hours before the trial ends."
- An existing subscription will normally continue until the end of its term and then just not renew. Stopping automatic renewal is effectively canceling it.
- Canceling a subscription does not automatically start a refund. If you want to do that:
Click on this link to "Report A Problem" to ask for a refund. --> https://reportaproblem.apple.com/?s=6
If Report A Problem does not work for a subscription refund you may have to make a special request. Click here --> https://support.apple.com/choose-country-region/media-services Select your country, then a product.
Apple's terms of purchase in the USA are, "All Transactions are final" (https://www.apple.com/legal/internet-services/itunes/us/terms.html), but some countries have different laws so check terms for your country at: https://www.apple.com/legal/internet-services/itunes/. If sales are final then it is Apple's decision if they want to grant a refund. You can always ask, and people do get refunds on a case by case basis, but Apple can also say no.