You can use the Find Files and Folders and search out any thing with *.pwl then delete these as they are the password caches. That way if a password has been set it will now have been deleted.
For bios passwords, you need to identify the reset link in the motherboard. Failing that, you'll have to remove the motherboard battery for a few minutes. needless to say you then need to reconfigure the various bios options for best performance.