Insert the flash drive into a USB port on your computer. Open the Diskpart utility by typing “diskpart” into the Windows search bar and selecting the “Diskpart” program. Type “list disk” and press enter to view a list of all available disks. Type “select disk #”, where # is the number of the disk corresponding to your flash drive. Type “clean” and press enter to erase all existing partitions on the disk. Type “create partition primary” and press enter to create a new partition on the disk. Type “format fs=ntfs quick” and press enter to format the partition as NTFS. Type “assign” and press enter to assign a drive letter to the partition. Type “exit” and press enter to close the Diskpart utility.