How to restore default configuration of Cisco PIX 501 firewall

[GeforceUser]

I am currently on Cisco PIX 501 firewall. It was initially configured by a network engineer who left our office. I want to make changes in it but I am unable to save any changes. How do I restore it to factory defaults? I know I need to reconfigure the firewall once and it would be tedious but I am ready to do, I just need the steps or tips to restore it to factory settings as it came before during purchase. Can you help me to get my work done?

[BiGMaCHiNe]

Step 1:- Log in to the PIX Firewall. (If you forgot the Cisco PIX 501 firewall password, just refer this guide Password Recovery Procedure)
Step 2:- Once logged in, enter the global configuration mode and issue one of these commands:

clear config all
write erase

Step 3:- Reload the PIX Firewall.

[Baltazar]

All you need is the "PDM" or Pix Device Manager of Cisco. It helps you to restore the firewall to its factory default settings. Pix Device Manager runs using a web browser. Just go to Pix Device Manager and click on "File" and then select "Reset PIX to Factory Default Configuration". That's it.

[Aleksandra]

Try using a terminal emulation program (TELNET) and enter the following commands:

Step 1: configure factory-default [inside ip address [address_mask]]
Step 2: write memory

Description

The first step erases the running configuration and replaces it with the factory default configuration. The second step writes the factory default configuration to Flash memory.