How to Hide the "DEFINE SERVER" Admin Menu

function plt_hide_define_server_menus() {
	//Hide the "Settings → DEFINE SERVER" menu.
	remove_submenu_page('options-general.php', 'define-server/define-server.php');
}

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

Where do I put this code?