Data Removal
Facebook Login
If you have previously logged in with Facebook and granted Kueez access to your public facebook data, you can revoke access at anytime in the Facebook user interface at 

Facebook Messenger

If you want to unsubscribe from Facebook Messenger notifications, just reply unsubscribe to the Kueez user on Facebook.

Web Notifications

If you wish to unsubscribe from the app notifications, the notifications you receive are being sent to your browser (Google Chrome for example).
In order to remove them please check Google instructions for disabling notifications:

Here is a screenshot for your convenience: