Delete right sidebar and show the full width

Hey guys,

I love the Radiate theme and that is the reason why I use it. But one thing is annoying. So on the right side, I can’t delete the sidebar which shows “archive”, “search” and “meta”. So I was able that this disappears when I activate the “individual menu”. But my point is that I want to use the full width of the theme. Now I still have the problem that there is some grey empty space on the right side. So, how is it possible to set the settings or something in the CSS to use the full width. Does anybody have an idea ? The website is:
https://www.dj-skysound.de

Thank you already for your help. Have a nice Sunday.