WinToUSB

WinToUSB (also called Windows To USB) is a free Windows To Go Creator which allows you to install and run fully-functional Windows operating system on an external hard drive or USB flash drive, using an ISO, WIM, ESD, SWM, VHD, VHDX image file or a CD/DVD drive as the source of installation, or you can clone current Windows OS installation (Windows 7 or later) to a USB drive as a Windows To Go Workspace. WinToUSB also supports creating a Windows installation USB flash drive from a Windows 10/8.1/8/7/Vista/2008/2012/2016 installation ISO file, so you can install Windows from the USB flash drive easily.

http://www.easyuefi.com/wintousb/