Remove Categories and tag buttons…!

Hi All

Very new to wordpress and have a hard time finding the right answer for my problem
A friend of mine as started a site and would like to know how to remove the Categories and Tab links from
his post.
I read about CSS editing upgrade and theme specific css so check this site and please let me know how
to do this.
http://risingrockproductions.com/wordpress/our-work/

Thanks