How do I remove an image hyperlink

Hi, I’m using the Vigilance theme and every time I post an image, it is hyperlinked to the original image. The problem with this is that I can see a line (horizontal cursor) at the bottom of the image, which is an annoyance especially if my image is a musical staff and already contains 5 horizontal lines (see what I mean at my website http://www.tuunup.com). The extra line may confuse the reader. If I place the mouse on the image, the horizontal cursor at the bottom goes away. If I click on the image, I’m taken to the original sized photo.

I would like to remove the horizontal cursor that appears at the bottom of every image that I upload. Can someone help me please and let me know what I should do?

Thanks very much in advance and will be looking forward to your reply.

~TuUnUP