We cannot cancel your subscription for you. Instead, open the Settings app, scroll down and select iTunes & App Stores, then tap your Apple ID at the top of the page. From the pop-up box tap View Apple ID and log in. Now select the Manage option below the Subscriptions heading, then select Swipe. Turn off Auto-renewal at the bottom of the screen and tap Done. You can then delete the app from Newsstand.
Sometimes, if one of the buttons is greyed out, you will need to sign out and into your Apple ID on your device to complete the process