I’m sure there are smaller downloads that can remove a Windows password, but having a copy of one of these emergency boot discs should be a requirement for everybody.
There are several free utility CDs that incorporate an option to remove a Windows password. These include Hiren’s Boot CD (HBCD), Ultimate Boot CD (UBCD) and Ultimate Boot CD for Windows (UBCD4WIN).
This procedure uses Ultimate Boot CD (UBCD).
You need to use a working computer to download the .ISO image, and burn it to CD. You then use the CD to boot the computer that’s blocking you with a password.
This link takes you to a download for Ultimate Boot CD 5.1.1. Scroll down to Free System tools, and download the .ISO image, then burn it to CD.
http://100-downloads.com/
If you don't have burning software installed on the working computer, download and install Ashampoo Burning Studio 6. It's free, and I recommend it...I use it myself:
https://www.ashampoo.com/uk/gbp/pin/0710/0-Offline/Ashampoo-Burning-Studio-6
Start up Ashampoo and select Create/Burn Disc Images...then select Burn a CD/DVD/Blu-ray Disc from a Disc Image.
Burn the CD or DVD, and use it to boot your problem computer. You may need to enter your BIOS (Setup), and change the boot sequence to boot from CD first, but this isn't always necessary.
Once you’ve booted your problem computer with the UBCD, scroll down and click on “Parted Magic”, then scroll down again and click on “Alternate graphical server”. Allow it to load up, then click on the circular Parted Magic symbol in the bottom left-hand-corner of your screen.
Select “System Tools”, then click on “PCLoginNow”. Click the Next button, then highlight the system you wish to log in to. If you have multiple operating systems installed they will all be listed, so be careful to select the correct one.
Click the Next button. Now highlight the user. If you have multiple accounts installed they will all be listed, so be careful to select the correct one.
Place a tick in the box labelled “password is empty”. Click the Next button, and if asked “Reset successfully! Do you want to reset another USER?”, click the No button.
Once again, click on the circular Parted Magic symbol in the bottom left-hand-corner of your screen and select “Logout”, then select “Reboot the computer” and click the OK button.
CHKDSK will be activated. Allow this to complete and if all is well, you’ll continue to boot to your desktop.
Hope this helps.