Delete content to permanently remove it from a site
  library. Deleting a folder removes both the folder and its contents from the
  library.
    This task assumes you are in the library of the desired site. To
    perform this task on a folder the Show Folders
    feature must be enabled.
    This feature is also available for multiple selections.
    - Navigate the library’s folder structure to locate the content item or folder you want to work with.
 - Position the cursor over the content of interest in the item list to display the available actions.
 - 
        Click More and then Delete
        Document or Delete Folder.
        
A message prompts you to confirm the deletion.
 - 
        Click Delete.
        
The item or folder is deleted from the library.