I suppose it will be the easiest and quickest way to reset/remove the lost Windows administrator password with a Windows password recovery tool like Daossoft Windows Password Rescuer which can be searched through Google. It is an omnipotent program which works on any brands of laptop or desktop such HP/Dell/Samsung/Acer/Asus/Lenovo .etc. And it supports any versions of Windows such as Windows 7/8/8.1/Vista/XP .etc.
You just need to install the Daossoft Windows Password Rescuer into any accessible computer and launch it to burn it to a USB/CD/DVD flash drive. Then boot your password lost Windows from the flash drive to reset/remove its administrator password.