unable to remove the sidebar image from a "post"

hi everyone,
I have been trying to remove the sidebar from a post since hours now using techline theme. I got succeded in doing so but I still am not able to use the sidebar space thus unable to use the space in my content or lets say unable to widen up the space of that post . Aside from that I also want the grey sidebar background image to be removed so that i can give a white colour to the whole content page aside from header and footer.A little help would be appriciated.

PS. To remove the sidebar i deleted the ‘get sidebar’ call from single.php