Flexslider – Don't want the main image thumbnails to show

Here's the link : http://173.254.124.29/~maysix/maysixftp/shop/sigma-e20-short-shader/
I don't want the single product main image thumbnail to show when I have only one image in the gallery.

Here's the link with more then one image : http://173.254.124.29/~maysix/maysixftp/shop/sigma-e05-eye-liner-2/

Thanks