Delete / Erase / Change Password for the for the Cisco 2000, 2500, 3000, 4000, AccessPro, 7000 (RP), AGS, IGS, and STS-10x
Step 1: Hit ctrl / break directly after powering up the router.
Step 2: Type o, press ENTER, and record the current value of the configuration register (usually 0x2102 or 0x102).
Step 3: Type o/r 0x2142,and press ENTER
Step 4: Type i , the router will reboot but ignores the saved configuration.
Step 5: Would you like to enter the initial configuration dialog? [yes/no]: answer NO
Step 6: Type enable at Router>
Step 7:Type configure memory or copy startup-config running-config.
Step 8: Type show running-config.
Step 9: Type configure terminal to change or remove the password from the router.
Step 10: Type enable secret <password> in order to change the enable secret password or type NO ENABLE SECRET to remove the secret from router(config)#>
Step 11: type: NO ENABLE PASSWORD to remove the password from router (config)#>
Step 12: Type the no shutdown command on every interface that you use.
Step 13: Type config-register <configuration_register_setting>. For example: hostname(config)#config-register 0x2102 .
Step 14: Hit Ctrl / z or end to leave the configuration mode.
Step 15: Type write memory or copy running-config startup-config to save the changes.
Step 16: Type Reload