Bootable Flash Drive Partition From Windows

Run From Administrator: Command Prompt
You are now in DISKPART>
list disk
Note disk number (Starting from 0)
select disk #
To confirm type 'list disk' again and an * will mark selected disk.
Now clean existing partitions.
Now create primary partition
create partition primary
Now to format desired file system
select part 1
format fs=[fat,fat32,ntfs] quick
format fs=fat32 quick
Now make it active
Now you can exit disk part
Now you can copy your boot files, Ex: Grub, Grub2Win, WinPE, etc