How to Hide the "DDoS Protection" Admin Menu

function plt_hide_protection_against_ddos_menus() {
	//Hide the "Settings → DDoS Protection" menu.
	remove_submenu_page('options-general.php', 'paddos');
}

add_action('admin_menu', 'plt_hide_protection_against_ddos_menus', 11);

Where do I put this code?