How to Hide the "Post Type & Taxonomy Debug" Admin Menu

function plt_hide_post_type_taxonomy_debug_menus() {
	//Hide the "Tools → Post Type & Taxonomy Debug" menu.
	remove_submenu_page('tools.php', 'pttax_debug');
}

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

Where do I put this code?