forgot my laptop password

ok look my cousin gave me a laptop that he didn't use any more because he forgot the password. I can't call dell because i'm not the original owner, and there is a password on the bios. is there some type of master password or can you tell me how to take the cmoss battery off, or how to re-format the harddrive, thank you

 

You can open the case and pull out the battery, but that will be hard on a laptop.
KILLCMOS should be able to reset it via software. Your A/V might detect it as a virus because of the way it accesses the BIOS, but it is completely safe.