1. Run the command “diskpart” from the command line (<windows key> + r)
2. Select the USB key you want
select disk <number of your USB>
3. Erase the USB and reformat it
create partition primary
format fs=ntfs quick
4. Now you have a USB ready to run! Just copy all the files from a windows install DVD onto this USB and you should be able to boot from it, isn’t that unusually simple for a MS product!