Apple Devices:
To turn off notifications on Apple Devices, go to Settings > Notifications, and select the app apps you would like to change notifications for. For more information on Apple device notifications, please visit: https://support.apple.com/en-us/HT201925

Android Devices:
To turn off notifications on Android Devices, go to your device Settings > Sound > Apps > and select which apps you would like to change your notifications for. For more information on Android device notifications, please visit:
http://www.howtogeek.com/204187/how-to-disable-app-notifications-in-android/