Have been trying to cancel my optus sport subscription. I've read the FAQs / help page, but I haven't found them particularly helpful. I didn't use the Apple App store to purchase the account, I went online
If you do not have an Optus service (like mobile or home internet) and only the Optus Sport subscription you can unsubscribe with the following steps:
Settings > Select name > iTunes & App store > Apple ID > Subscriptions > Optus Sport > Manage Subscriptions > Unsubscribe.
If you're still encountering issues please let us know.