Remove undismissable WooThemes Updater notification: Install/Activate the WooThemes Helper plugin to get updates for your WooThemes plugins.

functions.php

add_action( 'init', 'remove_woothemes_updater_notice' );
/**
 *  Remove the undismissable admin notice to install/activate the WooThemes Helper plugin.
 */
function remove_woothemes_updater_notice() {
	remove_action( 'admin_notices', 'woothemes_updater_notice' );
}