There are a number of interdependent snippets of code throughout the file in recent versions of Cat Dressing, so I wouldn't advise deleting code without a full understanding of what you are doing. The readme tells how to disable examples you don't want to use.

You can definitely delete most of the stylesheet declarations that you are not using. The divider will occur above the heading text; if you want it below for all headings, you can simply add to your stylesheet's .catBoxHeading1 { declaration
Code:
border-bottom: 1px solid #112233;
Adjust to taste.