Code goes to your active theme’s functions.php file:
// allow only admin, employee and client to create shipment
function wpccustom_wpcfe_add_shipment_role_cb($roles){
$roles = array('wpcargo_employee', 'administrator', 'wpcargo_client');
return $roles;
}
add_filter('wpcfe_add_shipment_role', 'wpccustom_wpcfe_add_shipment_role_cb', 15, 1);