I thought I found this answer in the forums before, but I can't seem to find it again. When I set Category Title to Hide the title goes away, but a white box remains and I have no idea how to get rid of it. Not sure why this would happen when you just want to hide the title. I'm using the older version of K2 for a reason (plugins), but wouldn't think this to be such a hard thing to resolve.

Firebug should find this, look at the div, then be sure your using an override and edit the proper php file to remove the div or span alltogether