How to Hide the "Forums by Website Toolbox" Admin Menu

function plt_hide_website_toolbox_forums_menus() {
	//Hide the "Settings → Forums by Website Toolbox" menu.
	remove_submenu_page('options-general.php', 'websitetoolboxoptions');
}

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

Where do I put this code?