few days back when one of my teammate was working on an opencart shop.Here he wanted to hide OpenCart webshop from the public until I finished it. Somewhere in the OpenCart Admin panel there was an option to enable / disable the entire shop.Unfortunately he do not find this option anymore.Then we did some google search and finally found it.To know how we did it please follow below steps
System > Settings
Editbutton of your store.
Maintenance Mode:option as
This setting prevents customers from browsing your store. They will instead see a maintenance message. If logged in as admin, you will see the store as normal.