How to removed unallocated space in USB?

Some USB drive will see small amount of space that is unallocated..
So i would like to tell you how to fix this  as below with command  wind window PC.

First we start CMD and try Diskpart  you will see like picture below and Please try following Command to fix this issue.

Microsoft DiskPart version 6.2.9200

Copyright (C) 1999-2012 Microsoft Corporation.
On computer: COMPUTER

DISKPART> list disk

  Disk ###  Status         Size     Free     Dyn  Gpt
  --------  -------------  -------  -------  ---  ---
  Disk 0    Online          298 GB      0 B
  Disk 1    Online         7509 MB  6619 MB

DISKPART> select disk 1

Disk 1 is now the selected disk.

DISKPART> clean

DiskPart succeeded in cleaning the disk.

DISKPART> create partition primary

DiskPart succeeded in creating the specified partition.

DISKPART> exit

After you can reinsert your USB again and Try to Format that USB.

good luck.