Remove

I am trying to make a new landing on my site, and I want to remove the sidebar from this blank page. I've tried a few codes and nothing has worked. Does anyone know the right code?

https://www.matthewstith.com/slideshow

Try this in Custom CSS:

#collection-65c84a6c83c3f95166c41d6e {
  body.sidebar-position-left #headerWrapper {
    display: none;
  }
}

Still not working. The code is sitting in the header. Maybe i'm putting the code in the wrong place? I'm currently injecting into Page Setting -> advance. 

39 minutes ago, MDS_photo said:

Still not working. The code is sitting in the header. Maybe i'm putting the code in the wrong place? I'm currently injecting into Page Setting -> advance.

That is code injection not Custom CSS, go to Website -> Website Tools -> Custom CSS

Unfortunately Still isn't working. 

I've adjusted the code, try this instead:

#collection-65c84a6c83c3f95166c41d6e {
  #headerWrapper {
    display: none;
  }
}