There is an Apple article that explains how to cancel subscriptions. Click on the following link: If you want to cancel a subscription from Apple - Apple Support
or use an internet browser to cancel as described in How to cancel Apple TV+ - Apple Support
If there were charges from before it was cancelled, there is an Apple article with information about requesting refunds. Click on the following link: Request a refund for apps or content that you bought from Apple - Apple Support
If the option to cancel a subscription is missing, see the following excerpt from Apple Support article If you want to cancel a subscription from Apple - Apple Support
You might need to scroll down to find the Cancel Subscription button. If there is no Cancel button or you see an expiration message in red text, the subscription is already canceled.
Also, a subscription that is already cancelled will typically have wording in fine print similar to "Expires on [date]" rather than "Renews on [date].”