... try this ...
$sql_del_users = "DELETE FROM ".USERS_TABLE."
WHERE user_level = 2
AND user_t_images = 0
AND user_lastaction < ".(time()-$no_action*24*3600);
$result = $site_db->query($sql_del_users);
echo "Users deleted !";
... "user_t_images" is a additional_user_field ... "user_total_images" ... I think from [Mod] Keep Track Of Each action ...