Prior to Windows 8, I used a program called Virtual CloneDrive to mount ISO’s. Once the ISO was mounted, it could easily be unmounted by selecting the “Unmount” option:
ISO’s can natively be mounted in Windows 8, but there’s no “Unmount” option. To unmount an ISO, right click on the drive letter of the mounted ISO and select “Eject”:
While writting this blog, I also discovered that “Eject” is an option with Virtual CloneDrive as shown in the first image that can be used to unmount an ISO.