But the cheap fix might be to replace the hard drive. Almost all the machines I know require a return to the maker's service center to clear such passwords. Given shipping costs a new hard drive and using the restore media to get the machine running may be the cheap exit.

If you are more technically inclined you can remove the drive and wipe it clean with a software I note soon. This software wipes drives attached to the machine clean so always disconnect drives you do not want clean. The name of the software is DBAN.

I have stopped supplying direct links because some have run out and run it without reading the instructions.