Removing Windows user passwords

For this you need a toolkit USB loaded with a live CD tool as (deprecated, but still functional) "Hiren's Boot" or its spiritual successor (and loaded with tons of useful tools, very recommended!) "Medicat".

Medicat - Computer Diagnostic and Recovery Toolkit

HomepageHiren's BootCD PE

There's instructions/scripts to install them on a USB in their webs.

Once you boot the live CD there's a section with various password removal tools that edit the SAM file and let you change/remove the pass easily with a graphical interface. Just select the account you want to remove the password and follow the steps.

If live CD doesn't load directly and BIOS has a password, meaning you can't change boot order, you would need to open the system and remove the CMOS battery located in the motherboard for a couple minutes, so the BIOS resets to default.

Be very careful when editing SAM files and never do it on production systems if there's other way, as it can corrupt the file and leave the account inaccessible!