Remove standard menu items

From your WP dashboard, go to “widgets”, located under the “appearance” menu. Remove the widgets in the “Main Sidebar” area. You can also expand the widget and click “Delete” in the lower left hand corner of the widget.

I suggest removing/deleting one at a time and seeing the effect on your site.

Hope this helps!

Update: After removing/deleting all of the widgets, drag a “Text/HTML” widget into the Main Sidebar and leave it blank. This will tell WP to show nothing in the sidebar.