All done with HBO Now for, er, now? Did you decide Apple Music wasn't for you? Or an online magazine? It's no problem to cancel iTunes-based subscriptions like these -- provided you know where to find the cancellation option.
The location for that option changed with the arrival of iOS 11 earlier this year, so let's take a look at the new process for finding and cancelling subscriptions.
Step 1: Open the Settings app and tap the very first option, which should be your name.
Step 2: Tap iTunes & App Store.
Step 3: At the very top, tap your Apple ID. (This is what tends to confuse most users, as there's no arrow next to it or anything like that. Your natural inclination is to scan the items below your Apple ID.) Then, in the pop-up box that appears, tap View Apple ID.
Step 4: Confirm your account by signing in with your password or Touch ID. Then scroll down a bit and tap Subscriptions.
Step 5: Tap whatever subscription you want to cancel, then tap Cancel Subscription. Confirm the cancellation and you're done!
Obviously it would be a lot easier if iOS 11 would let you search for "subscriptions" in the Settings app (where you can search for just about everything else), but currently that's not an option.