If you're having nuisance pop-ups show up on your device when Google Chrome is open, it's likely that notifications got turned on for a specific site. Follow the directions below to disable these.
Disable Site Notifications In Chrome
At the top right, click More Settings.
Under the “Privacy and Security” section, click “Site Settings”.
Within the permissions list, click “Notifications”.
From here, you can either opt to completely disable notifications, or block specific problem sites from sending notifications.
Anything you don’t recognize should most likely be blocked, as some sites tend to send messages many people, understandably, would not want to see.