KarinUlli

We decided to solve this another way, so I mark this as resolved.

For me this worked:

Add this in your functions.php:

// Unregister Twenty Fourteen left sidebar
function remove_left_sidebar(){
	unregister_sidebar( 'sidebar-1' );
}
add_action( 'widgets_init', 'remove_left_sidebar', 11 );

Add this on top of style.css:

/* Removes left sidebar and centers site */
.site:before { display: none; }
#secondary { display: none; }
div { margin: 0 auto; }