Cisco: How to remove config from decommissioned switches

Use the following procedure:
1. Login to decommissioned switch.

2.  If you want to keep a backup of config for emergency, copy it from the switch to an ftp/tftp/scp server before wiping the switch:

copy run ftp://ftp-ipaddress/running-config.txt



3. Run the following command to remove the startup config file:

write erase

4.  Reload the switch to clean the running config in volatile memory using the following command:

 reload

WARNING: ONCE YOU RELOAD THE SWITCH ALL CONFIG IS GONE EXCEPT FOR THE MGMT0 IP ADDRESS, GATEWAY, AND BOOT VARIABLES THAT LOAD THE KICKSTART AND SYSTEM IMAGES!!!!

5. Once complete, the switch will be reset to factory default initial setup once the switch is back online..

Use extreme caution when executing the write erase command. it is not intended to be used on switches in active production environments unless you are intending to remove all config from the switch. It will disrupt traffic through the switch once you reload and will not recover existing config once it is back online.  

If you run the write erase command by accident, DO NOT RELOAD THE SWITCH if you want to keep config. As long as you have not reloaded the switch, you can still copy the active running config to the startup  config with the following command. this is non disruptive:

copy run start

If you need to recover from a saved config file created at step 2, run the following command to copy it back to running config from the ftp server:

copy ftp://ftp-ipaddress/running-config.txt run