Step 1: Click on your username displayed in the top right hand corner of the page and click through to 'Account Settings'.
Step 2: Scroll down until you see the 'Channel Pack Subscriptions' section. Below it will list the package that you are subscribed to and you will see a link beside it that allows you to remove the package. Click on 'Remove Package'.
Step 3: A dialog box will appear asking you to confirm that you want to cancel your subscription. Click 'OK' if you want to remove the package. Once you have clicked okay, the package will cease with immediate effect.