Invalid notification problem!

Once I received 3 upgrade-complete notification messages. I didn't respond to them at once, but when I clicked one of them entering the game, the number kept displayed on the upper-right corner of the app icon as follow:

Please tell me how to remove those 3 dead notifications, which I couldn't remove. Or please add a function to remove all notifications from the notification center. Thank you.

Your image didn't appear but in general to delete all notifications for an app on iOS it lists the app name in a banner thing with the specific notifications listed below it. There is an "x" to the right on the banner which you can press and then it changes to "clear". Press this "clear" button and it will delete all notifications for that app that are in notification center.