If you want to completely disable the link of that photo, you should delete 29th and 31st line of your code (29th is the one with lightbox class, 31st is simply < /a>).

If you want photos to link somewhere else, it will need custom coding. You may want to change:

<?php echo wp_get_attachment_url( $myPhotoID ); ?>

placed in the 29th line of code to your desired value. Please keep in mind that I am working on unchanged version of that file, so lines of code might be different (if you changed anything in that file before).

Let me know if it helps you.

Thank you,