If you have mistakenly lost your password to the computer BIOS password or you receive a password at boot you will need to clear the BIOS password by one of the following methods.

Precaution: When inside the computer please be sure of the potential of ESD. (Electro Static Discharge)

On the computer motherboard locate the BIOS clear / password jumper or dipswitch and change its position. Once this jumper has been changed turn on the computer and the password should by cleared. Once cleared turn the computer off and return the jumper or dipswitch to its original position.
The location of the jumpers or dipswitches may vary, however here are general locations where these
jumpers / dipswitch may be located.

On the edge of the motherboard - Most jumpers are located on the side of the motherboard for easy accessibility, verify by looking at all visible edges of the motherboard.
By the CMOS battery - Some manufactures will place the jumper to clear the CMOS / BIOS password by the actual CMOS battery.
By the processor - Some manufactures will place the jumpers by the processor of the computer. However note that in some cases these jumpers will be to change the processor and not the password.
Under the keyboard or bottom of laptop - If you are working on a computer laptop the location of the dipswitch (almost never a jumper) can be under the keyboard or on the bottom of the laptop in a compartment such as the memory compartment.
Other visible location - While it is possible that the jumpers / dipswitches may not be in a visible location, most manufactures try to make things easier by placing the jumpers / dipswitches in another visible location.
Additionally, when looking for the jumper / dipswitch the label of that switch can be anything however in most cases will be labeled CLEAR - CLEAR CMOS - CLR - CLRPWD - PASSWD - PASSWORD - PWD.

On the computer motherboard locate and remove the CMOS battery for at least 10 minutes allowing the computer to loose its information. Note: this will not work on all computers.
If your manufacturer has a bypass password this can be entered and allow you access to the BIOS and or computer. Because of the security risk of a bypass password generally only older computers will have this option. In addition it is likely that this information will only be able to be obtained from the computer, motherboard or BIOS manufacturer.
On the computer motherboard locate the CMOS solider beads and jump the solider beads to clear the password. The identification and location of these solider beads can vary and if not available in computer documentation is generally only obtainable through the computer manufacturer.
If one of the above solutions do not clear the password or you are unable to locate the jumpers or solider beads it is recommended you contact the computer manufacturer for the steps on clearing the computer password.