Sounds like she may have set a BIOS password. You would have to find the manual for the type of motherboard it is to find which jumper to remove.
If it is the Windows Password, that will not work, no. Typically people do not set BIOS passwords; most are not aware you can or how to do it. The only thing you can do if this is the Windows password is re-install the OS unless she is willing to give you her pw and then you can create a new account and delete hers.