If you subscribed via iTunes, your subscription is directly with Apple - so you will need to into you iTunes to cancel the subscription. Please follow Apple's step-by-step instructions in each country:

or you can follow these steps:

  1. Go to the Apple Store
  2. Click on 'Featured'
  3. Scroll down the screen to the 'Apple ID'
  4. Click on 'Apple ID' and then 'View Apple ID'
  5. Enter your Apple ID password
  6. Scroll down to 'Subscriptions' and click on 'Manage'
  7. Slide the auto-renewal bar to OFF
  8. A pop-up box will display asking you to 'Turn off Auto-Renewal', toggle to 'Turn Off'
  9. When you return to the page, you will see that the Auto-Renewal toggle is off
  10. You will be able to access H&C until the end of your subscription. You will receive an email from Apple confirming your cancelled subscription and the date you will lose access to H&C.

If you are still unable to cancel (or are having any other problems) please email support.