You can also change a little-known setting that still keeps your password, but doesn't require you to enter it on log-in (it will be automatic).http://www.howtogeek.com/howto/windows-vis...-automatically/
But the same affect is achieved (automatic login). If you want anybody to have access to your computer (automatic login, which is a bad idea), then the best option would be to have a blank password. The reason for this is that if you have a password and don't require it to be entered (like in the tutorial), you will likely forget it, and could possibly lock yourself out forever.
But like MrBruce1959 said, if you are talking about the "system password" in the BIOS, that is another story all together. It will require disabling in the BIOS.