Hey Kari,
in WordPress, the sidebar is inserted by the “get_sidebar” template tag. To remove the sidebar from category pages, you’ll need to edit the “category.php” file found in the root of the theme, line 52 is what you need. When you remove the sidebar from the php file, the content will still remain left-floated and take up only part of the width because of the CSS declarations; you’ll need to add a CSS override to “style.css” saying something like this:
.category #content { width: 100% !important; }
I hope this helps. Let me know if there are any difficulties with the process!
Sincerely,
Andrew / Satori Studio