When you receive unwanted notifications from an app, touch & hold the notification, then tap Turn off notifications.
To review all apps and adjust whether they can send notifications:
Do one of the following:
Change to Silent
If you want an app's notifications to be less intrusive, you can categorize them:
Option 1: On a notification
Option 2: In Settings
To adjust the volume level of all notifications:
Set default notification sound
To change the sound used for notifications from all apps:
Do one of the following:
Set notification sound for a specific app
To use a distinctive sound for an app's notifications, instead of the default notification sound:
Tap the category for enabled notifications, then tap Advanced > Sound and select a unique ringtone, or set it to none.
If you can't hear a notification
To let an app's notifications be heard when Do Not Disturb is on:
If an app isn't sending notifications but you want it to:
If you want to be able to snooze your notifications, turn on snoozing:
App icons show dots to alert you about unread notifications. You can turn off dots for one or all apps.

Turn dots off for all apps
Turn dots off for one app
If you've set a pattern, PIN or password, you can control which type of notifications show on your lock screen and prevent them from revealing private information.
To adjust notifications for all apps:
To hide sensitive content on your lock screen, turn Sensitive notifications off
.
You’ll get lock screen notifications for an incoming email or chat, but they won’t include message details.
For finer control, leave this on
to allow details, and instead hide sensitive content from specific apps.
To hide sensitive content from specific apps:
Types of notifications the app sends appear here. For each enabled notification that you want to hide: