From the Chrome support site:
https://support.google.com/chrome/answer/3220216?hl=en
-On your computer, open Chrome.
-At the top right, click More (the three dots) and then Settings.
-At the bottom, click Show advanced settings.
-Under "Privacy," click Content settings.
-Under "Notifications," choose one of the following:
-Allow all sites to show notifications: You’ll automatically see notifications from all websites.
-Ask when a site wants to show notifications: You’ll get an alert from Chrome whenever a site wants to show you notifications. This is the default setting.
- Do not allow any site to show notifications: You won’t see any notifications from websites.
You can also block any sites, apps, and extensions that already have permission to send you notifications. Just click Manage exceptions.