You would need to modify the CSS code that sets the width of the element(s) still on the page. Do be aware, however, that you should never modify theme files directly, but rather use a child theme for your changes. That way, the changes won’t be overwritten when the theme is updated.
I have a very similar question about changing the featured categories section. When I try to change the CSS to have 3 of them fall onto the same line, it doesn’t react as expected.
When I look through the code, there’s a <div class=”clear”></div> that seems like is being generated somewhere along the line… also, feat cat 2 is given the class “.right-side” and I can’t figure out where… I’ve looked through the feat-cat2.php and I can’t figure out where either the class is being added or where that clear is coming from. (I’m familiar with HTML and CSS but new to PHP)