What is it you need the Command Line for. If it's really needed you can back out of the install by clicking the Red X, reboot into Installer System Recovery Options.
Do you have the EFI boot disk set to boot first in BIOS setup, and other settings for EFI correctly set. You may need to consult the Manual on the mobo or PC's Support Downloads webpage.
If you'd like to bypass EFI then enable Legacy BIOS, set DVD drive to boot first, wipe the HD with Diskpart Clean Command