If you want to disable Shortcode Generator for some "non technical" users, you can add next snippet to your theme's functions.php file
update_option( 'su_generator_access', 'administrator' );
administrator - is a minimal user role to access Shortcode Generator. You can replace it with editor or even any other user role you've created. Also, you can replace it with any user capability. See this Codex Page for more information.
If you want to remove this restriction just replace this snippet with next one
delete_option( 'su_generator_access' );