I always use NT password recovery with YUMI to bring NT password recovery to a USB drive. You can then boot from USB and reset or delete any user password.
YUMI is very easy to use. Just download YUMI and the ISO, start YUMI and select your USB drive (you have to check "Show ALL Drives? (USE CAUTION)" if you're using a USB HDD), boot from USB and follow the menu in NT password recovery.
If you've problems with NT password recovery, you can check their website for more information on usage or ask here.
If you're not sure which ISO file to download, use YUMI to find out.
YUMI helps you to find the right download and even directs you to the download.
Just search for
Offline NT Password & Registry Editor and check the
Download the zip (Optional) checkbox next to the list:
As you can see, YUMI also shows the file name below the list painted red because the ISO file isn't yet in my download dir. It'll change that text color to green if when it found the right ISO file in your download dir.