Apache & Zen Cart will do that automatically. A properly setup Apache can use either URL and within the Zen Cart config files, you can be specific.
Example of includes/configure.php
define('HTTP_SERVER', 'http://yourdomain.com');
define('HTTPS_SERVER', 'https://yourdomain.com');
The URL will now automatically, not use the 'www'.
It all goes back to the Domain name used in the Cert, as to whether the 'www' should be used or not.




