How to Hide SSL Zen — SSL Certificate Installer & HTTPS Redirects Admin Menus

function plt_hide_ssl_zen_menus() {
	//Hide "SSL Zen".
	remove_menu_page('ssl_zen');
	//Hide "SSL Zen → SSL Zen".
	remove_submenu_page('ssl_zen', 'ssl_zen');
	//Hide "SSL Zen → Affiliation".
	remove_submenu_page('ssl_zen', 'ssl_zen-affiliation');
	//Hide "SSL Zen → Contact Us".
	remove_submenu_page('ssl_zen', 'ssl_zen-contact');
}

add_action('admin_menu', 'plt_hide_ssl_zen_menus', 1000000000);

Where do I put this code?