Post Page > Exclude Cat Link?

Hello I’m trying to exclude a specific categories link that you see on a post page by the entry meta content. So you’ve got your post title, the author, date, etc and then the categories the post is featured in.
Well, I want this to be a hidden category that doesn’t show up on the post page but can still be used for internal/tech reasons.

I thought about maybe css and just doing a display:none if anyone knows the css code to call to the specific category tag id or also I’ve tried going into the functions.php but i’m using a moded twentytwelve theme and I’m not 100% positive how to do this.

any help greatly appreciated! again not trying to exclude any post just one specific category link that goes with the post… I want it to be non visible.