Unfortunately Windows does not support Fdisk anymore. But there is another good command line tool to solve this problem. The tool’s name is DiskPart. I would say it is the next generation of Fdisk tool. DiskPart provides you information about your partitions and volumes, allows you to delete and create partitions, extend NTFS volumes, etc.
Let’s remove unallocated space. First of all run Windows command line and type diskpart in the command prompt. Windows will ask you for Administrator permissions to run the tool. Then run list disk command to find your USB flash disk’s number. It should be the same as disk’s number in Computer Management tool. It was 1 in my case. Next you should chose the disk to work with. Type select disk
This is how I removed unallocated space on my machine:
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 succeeded in cleaning the disk.
DISKPART> create partition primary
DiskPart succeeded in creating the specified partition.
if you have any other options so don't forget to comment it in below.