plug into another PC using a usb caddy
the drive will appear in disk management either right click and select format (do not do a quick format) or you could use command prompt (admin) and run diskpart to remove all partitions and make just one partition on the drive before formatting.
refit in the laptop
ensure DVD is set as first boot device
insert DVD and and press any key to boot from he windows iso (DVD must be bootable made using windows media creation tool for w 10).
follow the prompts to install windows (you cannot install windows onto the drive while it is in the us caddy on the other PC).