Remove sidebar in WordPress

First, you need to determine the class of your content section in single post (single.php), for example :

Here it is “columns nine”.

Then in your theme skeleton, i.e. theme > lib > css > skeleton.css :

Replace :

.nine.columns {
    width: 74.5%; }

With :

.nine.columns {
    width: 100.0%; }

Then in single.php, remove :