How to Hide the "WOVN.io" Admin Menu

function plt_hide_wovn_io_menus() {
	//Hide the "Settings → WOVN.io" menu.
	remove_submenu_page('options-general.php', 'wovn-setting-admin');
}

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

Where do I put this code?