Removes any and all partition or volume formatting from the disk with focus. Syntax: CLEAN ALL ALL Specifies that each and ...

     Removes any and all partition or volume formatting from the disk with
     focus.

Syntax:  CLEAN [ALL]

    ALL         Specifies that each and every byte\sector on the disk is set to
                zero, which completely deletes all data contained on the disk.

    On master boot record (MBR) disks, only the MBR partitioning information
    and hidden sector information are overwritten. On GUID partition table
    (GPT) disks, the GPT partitioning information, including the Protective
    MBR, is overwritten. If the ALL parameter is not used, the first 1MB 
    and the last 1MB of the disk are zeroed. This erases any disk formatting 
    that had been previously applied to the disk. The disk's state after 
    cleaning the disk is 'UNINITIALIZED'.

Example:

    CLEAN