On your Mac, use Notifications settings to specify when you don't want to be disturbed by notifications, and to control how notifications are shown in Notification Center. To change these settings, choose Apple menu > System Settings, then click Notifications in the sidebar. (You may need to scroll down.)

In the Safari app on your Mac, choose Safari > Settings. Click Websites, then click Notifications. Deselect “Allow websites to ask for permission to send notifications.” From now on, when you visit a website that wants to send you notifications, you aren't asked.

Open Notification Centre: Click the date and time in the menu bar, or swipe left with two fingers from the right edge of the trackpad. Close Notification Centre: Click anywhere on the desktop, click the date and time in the menu bar, or swipe right with two fingers towards the right edge of the trackpad.

To remove an app from the Notification Center on your Mac, click on the Apple icon → Click "System Preferences" → Click "Notifications" → Click on an app → Uncheck the box next to "Show in Notification Center."