Hi
You need to read the Dell service and user guides or contact Dell technical support
Clearing the CMOS does not clear passwords on business class laptops
It would on most desktop motherboards
Laptops usually store passwords in an eprom chip
(Electronic programed read only memory)
Providing this is a password protecting the bios settings not the one preventing power up, the password can be cleared by a Dell main dealer or Dell themselves provided you can provide proof of ownership
Regards
Mike Barnes