Compaq Evo N610c help!

i have an evo N610c which is supplied through my work. the lease
however has run out and it now is myne. however i do not have the
administrator password for the bios so i am unable to install or format
anything to do with the hard drive. Whenever i try to install a new OS
it asks for an admiistraor password and will not let me proceed
further. this password also locks me out of the bios. i have tried to
research this with no luck. if anyone has any ideas on how to get
passed this it would be a lot of help.

i thought of resetting the bios by removing battery to do so. however i
can only find 1 and remove one battery (apart from the obvious laptop
running battery) and when removed this does nothing.

any suggestions would be very helpful thankyou