Suspicious pop ups may sometimes appear in the bottom right of your screen which can be found in the Notification Center:
When expanded, they may look like this. In this case, the notifications are coming from Chrome (as highlighted). Here is how to identify tell-tale signs of for this kind of scam.
At the top for whatever notification is the application it's coming from - if it's Chrome, it will be rogue notifications.
- If you then look at the notification details, it tells you what website the notification came from. To remedy this go to Chrome's settings, type site settings at the top, click into site settings, then find the website, and block notifications.
It may be worth blocking all permissions for the unwanted site - better safe than sorry!