LOL - well at least that's better than hanging the person! .
Anyway, what do you actually mean by "hang someone password"? - you want to hack their password, or disable their password, or what? If the latter, and you're talking about a computer, you'll need admin rights on the machine in question, and then depending on your OS, go to the control panel (in XP anyway) and click on user accounts. Then you can pretty much do whatever you want, including deleting their account.
Or just set a password in the machine BIOS so that they can't use the machine at all. Of course, they could always pull the CMOS battery and wait a few minutes to reset all BIOS settings to the default state, which includes no bootup password.