Removing sidebar // Can’t change Background

Hi!
I am customizing this theme:
https://demo.freebiesdock.com/
here:
https://www.300acres.com/

I dropped one of the two sidebars but I cannot seem to figure out what part of the CSS will remove the bg image that fills the space on the right {between the post content and the remaining sidebar}

I think i have tracked it down to this line but am not sure:

#content { width: 460px; _width: 449px; padding: 16px 15px 16px 14px; color: #55554e; font-size: 1.2em; line-height: 1.2em; float: left; display: inline; }
#home #content { width: 608px; padding: 16px; _padding: 15px; }

Any Suggestions?
Thanks so much!
~Sh?laco