How to Hide the "Fail2WP" Admin Menu

function plt_hide_fail2wp_menus() {
	//Hide the "Settings → Fail2WP" menu.
	remove_submenu_page('options-general.php', 'fail2wp');
}

add_action('admin_menu', 'plt_hide_fail2wp_menus', 11);

Where do I put this code?