PopUp and Ajax login not working as intended

Hey I am using PupUp Pro plugin with ZM ajax https://wordpress.org/plugins/zm-ajax-login-register/ plugin.
Here is my site: http://wowdesigns.in/projects/nesties
Please tap on "Join Us" you can see PopUp tap on "Already Registered" post that there will be a popup behind the existing PopUp.

My question is: Can you tell me how can I make the front screen disappear if I tap on "Already registered"?

Please let me know.

Thanks much.