How to un-configure a cisco router and erase the configuration to factory default?

Summary:

The purpose of this post is to quickly show you how to un-configure your cisco router and erase or reset the configuration back to factory default.
This post assumes that you have the access password to privileged EXEC mode of your router.
If you don't have access to the password, there is another post that i wrote on how to recover the password of your cisco router without loosing your current configuration.

Problem or Goal:

Our aim is to un-configure and reset a cisco router

Cause:

It's advised to always erase your router configuration before selling them in the refurbished market or before donating them to another organisation.

Solution:

1. Log in to the privileged EXEC mode of your router (make sure you have the enable password to your router)

MY_TECHIE_GUY_LAB01#

2. Enter the configuration mode

MY_TECHIE_GUY_LAB01#configure terminal

3. Change the configuration register as follows:

MY_TECHIE_GUY_LAB01(config)#config-register 0x2102

4. Type "end" to go back to EXEC mode

MY_TECHIE_GUY_LAB01(config)#end
MY_TECHIE_GUY_LAB01#

5. Type "write erase" to delete all configuration files from the memory

MY_TECHIE_GUY_LAB01#write erase 
Erasing the nvram filesystem will remove all configuration files! Continue? [confirm]
[OK]

Erase of nvram: complete

6. Type "reload", and answer the system prompts as follows:

MY_TECHIE_GUY_LAB01#reload 

Do you want to reload the internal AP ? [yes/no]: y

Do you want to save the configuration of the AP? [yes/no]: n

System configuration has been modified. Save? [yes/no]: n

Proceed with reload? [confirm]

7. The router will now reboot, answer "no" when asked to enter the initial configuration dialog?

         --- System Configuration Dialog ---

Would you like to enter the initial configuration dialog? [yes/no]: n



Press RETURN to get started!

Problem Solved?

Your router config is now back to the original factory default.

Router>
Router>en
Router#