function plt_hide_si_captcha_for_wordpress_menus() {
//Hide the "Settings → SI Captcha Anti-Spam" menu.
remove_submenu_page('options-general.php', 'si-captcha-for-wordpress/si-captcha.php');
}
add_action('admin_menu', 'plt_hide_si_captcha_for_wordpress_menus', 11);