How to Hide the "Garden Gnome Package" Admin Menu

function plt_hide_garden_gnome_package_menus() {
	//Hide the "Settings → Garden Gnome Package" menu.
	remove_submenu_page('options-general.php', 'ggpkg');
}

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

Where do I put this code?