Blog Full Width & no Sidebars does not seem to remove sidebar

In customizing basic settings I select:
“Blog Full Width & no Sidebars”
But when I inspect the page I see this:
div class col-md-9 has width of 75% (where content is placed)
and this:
div class col-md-3 to the right of div above, with 25% width.

In other words. The full width of the blog is not used for the content, since there is an empty right colum present which takes 25% of the width.

I also use:
Page width:
“Smaller Width 1200px”
and have also tried:
“Full screen”

But both gives same result.

Is this a bug, or what?

What is the best way to get rid of the right column, and get at true “Blog Full Width”?