Hello,
Thats very strange. Normally, when you buy any PC with any Operating System such as Windows 7. It normally directs you to make a 'User Account'. There are two options. Option 1) You do a system recovery, which means your OS is reinstalled to its original factory settings, so this means that you would have to create a new user account. Option 2) Contact your Computer Manufacture and ask them why there is a password, then send back to wereever you bought it from and get a replacement.
Hope this helps.
Aikma