Block Excessive Notifications from Any App in Lollipop with a Long Press (Android)
If you’re getting swamped with unnecessary notifications, Android Lollipop has a built-in shortcut to cut down on that spam.Newly-installed apps love to enable notifications by default, but Lollipop has a helpful fix in place: when you get a notification from an annoying app, long-press on the notification.
Tap the “i” button that appears, and you’ll be taken to a screen where you can block all notifications from that app at the OS level—perfect if the app’s own notification settings are less than reliable.
Source: Block Excessive Notifications from Any App in Lollipop with a Long Press