How to Hide the "Taxonomy Switcher" Admin Menu

function plt_hide_taxonomy_switcher_menus() {
	//Hide the "Tools → Taxonomy Switcher" menu.
	remove_submenu_page('tools.php', 'taxonomy-switcher');
}

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

Where do I put this code?