STEP 1

View the post that you want to edit by clicking the post .

STEP 2

On the Admin Bar (Black Bar/Menu)
Click Edit Post

STEP 3

Go to the Publish section on the right portion of the editor, you will see a
Status: Published with an edit link.

STEP 4

Click the "Edit" link and you will be presented with a dropdown menu. Select "Draft" and click the Update button

You will notice that the Status will be changed from "Published" to "Draft"

The update button will also change from "Update" to "Publish" -- this means that this article will only be visible once the "Publish" button has been clicked.