Cisco PIX 501 Firewall

Hi everyone,
I have a client who has a Cisco PIX 501 Firewall. The client is facing the following problem
He cannot remember his login information for the PDM.
He can get into the console but cannot reset to factory defaults.
I have serached Cisco websites for informations and directions to perform this task but was not successful.
Is there anyone here that had this problem and was able to reset the Cisco PIX 501 Firewall to factory defaults? If so can you help me help my client?
Thanks a bunch!