Removing 'Previous' Navigation Button

I hope you can help.

I really love this creative plugin, but need to know how to remove the ‘previous’ navigation button – the one that looks like this <.

I’ve tried editing the .png to leave only ‘>’, but all that does is reposition ‘>’ where ‘<‘ used to be.

I’ve also tried to insert display:none where the ‘previous’ navigation is called, but that didn’t appear to do anything.

Ideas, anyone? Many thanks for you help in advance.

http://ww.wp.xz.cn/plugins/slideshow-jquery-image-gallery/