Or just nuke it and do a fresh install, either with a DVD or a bootable USB pen.
Or grab one of the many Windows PE images, boot to that, create a new Admin account and its done, or boot with a dvd/pen with install media, repair, open a prompt and create a new Admin account.
Win is SOOOO easy to bypass, Win10 with Hello and whatnot?
PE boot, new Admin account, done, easy.