You can't. The last version of Windows where it could be done was Windows 98. After all, what's the use of a password if it can be bypassed so easily?
And to be exact: Windows doesn't have a password. A Windows account has a password. And http://windows.microsoft.com/en-CA/windows-vista/Create-a-password-reset-disk tells you how you could have made a reset disk, to use in case you forgot the password (but then you shouldn't forget where you stored that disk ). There are other ways also to reset the password. But that's not the same as bypassing it.
how do i bypass the windows password for windows vista and 7