Episode XOXO is part of Apple Arcade.

To cancel Episode XOXO, you must cancel your Apple Arcade subscription.

Here is a helpful tutorial from Apple on how to cancel a subscription:

https://support.apple.com/en-us/HT202039 

For any issues with cancellations, achievements, and leaderboards, please contact Apple support here:

https://getsupport.apple.com/solutions 

• Under Apps & Services, tap on 'Apple Arcade'.
  • If you do not see it, you may need to tap 'more' to expand the list.