If you signed up for CBS All Access via iTunes, you can use the steps below, or visit https://support.apple.com/ to contact iTunes Support.

On your iPhone or iPad

  1. Open the Settings app.
  2. Tap your name.
  3. Tap Subscriptions. (If you don't see "Subscriptions," tap "iTunes & App Store" instead. Then tap your Apple ID, tap View Apple ID, sign in, scroll down to Subscriptions, and tap Subscriptions.)
  4. Tap the subscription that you want to manage.
  5. Tap Cancel Subscription. If you don’t see "Cancel Subscription," the subscription is already canceled and won't renew.

Via Apple TV 4
On Apple TV, you can edit subscriptions only for tvOS apps that are installed on that Apple TV. For Apple TV (3rd generation or earlier), use an iOS or iPadOS device or computer to manage your subscriptions. 

  1. Open Settings.
  2. Select Users & Accounts, then select your account.
  3. Select Subscriptions.
  4. Choose the subscription that you want to manage, then select Cancel Subscription. If you don’t see Cancel Subscription, then the subscription is already canceled and won't renew.