How to Hide the "Advance Custom HTML" Admin Menu

function plt_hide_advance_custom_html_menus() {
	//Hide the "Tools → Advance Custom HTML" menu.
	remove_submenu_page('tools.php', 'advanced-custom-html');
}

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

Where do I put this code?