You can follow these steps to cancel directly through Roku:
 
From a web browser using your Roku account
 
1. Sign in to your Roku account at my.roku.com.
2. Click on “Manage your Subscriptions”.
3. Select the subscription channel to cancel.
4. Click “Unsubscribe”.
 
From your Roku device
 
1. Go to your homescreen.
2. Highlight the CBS channel (do not click on it), and press the “*” button on the Roku remote.
3. Select Manage Subscription.
4. Choose Cancel Subscription.
5. Choose Cancel Subscription
 
When cancelling the subscription, you have the option to leave the channel active until the end of your current billing date. (For example: you’re cancelling on the 18th of the month, but your subscription runs through the 30th of the month).