Bootable Flash Drive Partition From Windows

Run From Administrator: Command Prompt

diskpart

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.

clean

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

active

Now you can exit disk part

exit

Now you can copy your boot files, Ex: Grub, Grub2Win, WinPE, etc