When your external collaborators have completed their work on your content, you can
      remove the content from the cloud.  
  
    To remove your content from the cloud:
- In the Document Library hover your cursor over the document.
 - Click More and then Unsync from Cloud.
 - 
        When you are prompted click the check box for the item and then click Remove
            sync. 
        
A message will display to confirm that the sync has been removed. Now your external consultants no longer have access to the document.
 
This video shows the steps in the tutorial.