Removing Left Sidebar

Hi Everyone

I am trying to remove the left side bar from all of my pages, in dashboard in Atahualpa themes options i have left out the left sidebar – but the Categories and Archive headings are still present and showing up under my main text..I tried to find where to remove the sidebar in the theme templates but the index.php does not have anything referring to sidebars?

sorry not sure what version of wordpress i am using – as not sure where to find this information, as you can see I am just beginning to feel my way around..