To unsubscribe web push notification in chrome, (push notification for web doesn't support incognito mode)
- Click on the Secure button (green lock) in address bar.
- Select notification dropdown.
- Click and set as to "Use global default" (Prompt will be asked again to resubscribe)
- Reload the page. (Delete all the cookie to troubleshoot and retry)
To permanently block receiving website push notification, select always block on this site option.
To unsubscribe website push notification for firefox,
- Click on site information button near secure lock in address bar.
- Revoke the allow permission for push notification.
Permissions can also be revoked from site settings in the settings tab of the browsers.