In this quick tutorial I will show you how to remove sidebar border from Divi default pages.
CSS I used
#main-content .container:before {
width:0;
}
.et_pb_widget_area_right { border-left:0 !important; }
.et_pb_widget_area_left { border-right:0 !important; }
Can you be more specific about the content of your article? After reading it, I still have some doubts. Hope you can help me.