Using DiskPart To Clean A USB Thumb Drive or SD Card

If you have installed a Portable or Linux OS on a thumb drive or SD Card, Windows typically won't be able to reformat it for other use. To work around the limitations of File Explorer you can call DiskPart into service to help solve this problem.

Steps:

Insert the USB Thumb Drive or SD Card
Run CMD.exe as Administrator
C:\>diskpart

DISKPART>list disk
DISKPART> select disk 1
Disk 1 is now the selected disk
DISKPART> List Disk    (to verify selection (marked with asterisk to left of row)

*VERY Important Note: in my case since I only have a single internal hard disk in my laptop, the USB drive shows as disk 1, an 8GB stick.  If you have more than one disk already installed/mounted on your PC, then modify the select statement accordingly to point to your target USB device. If you select the wrong disk you could wipe out all of the data on your PC.

DISKPART> clean
DiskPart succeeded in cleaning the disk.

*note: when you execute List Disk if there is an * in the GPT column, the disk is formatted as a GPT partition. If no * is present, the disk is MBR. To change the format, you can type: convert MBR to convert GPT to MBR or convert GPT to convert MBR to GPT.

DISKPART>create partition primary
DiskPart succeeded in creating the specified partition.

DISKPART>active
DiskPart marked the current partition active.

DISKPART>format fs=fat32 quick
   100 percent completed.
DiskPart successfully formatted the volume.

DISKPART>assign
DiskPart successfully assigned the drive letter or mount point.

DISKPART>exit

C:\> exit   (to exit CMD window)