One way is to plug a USB drive into one of your computer's USB ports, then go to Control Panel>User Accounts>User Accounts>Create a password reset disk. When the Forgotten Password Wizard opens, simply follow its instructions to quickly create a password reset USB drive.
There are also several freeware apps that wipe the passwords from Windows. Click below:
[link|http://www.chntpw.com/download/|Here is one]
Be sure to read the directions, etc. before attempting.