This functionality is available for PRO version
The admin-ajax.php is being used by WordPress core and many plugins to initiate AJAX calls from dashboard and front side. This is specific to WordPress, a site using such slug is an easy target to hack attempts.
Default url can be found in html source like this
or like this
var ajaxurl = '/wph-admin/admin-ajax.php',
Rewriting the admin-ajax.php to another slug to increase overall security for a WordPress site. It also allow to restrict admin access for a range of IP’s without disabling the admin-ajax.php functionality calls.