Answer:
== Answer ==
If it's a desktop PC, erasing the cmos memory will usually clear it. Turn the power off, remove the cover. There should be a battery, these days they use a large silver disc watch battery type. Near it should be three pins with a linker on two of them. Move it to the other side, so the middle pin is linked to the other pin. Leave it there for a few seconds and then put it back in it's original position.
Replace the covers and boot up. You will then have to reset your BIOS options etc..
On Laptops, they all most always write the password to EEROM or flash memory, which don't need a battery. Unfortunately, sometimes the only way to clear these, is to remove the chip and use a programmer to load it with the latest BIOS from the manufacturer or replace it with a new one. Dell computers have a master password which is unique to each computer. That password can be obtained from Dell customer service.