Delete / Erase Password on Cisco routers keeping the config
Step 1: hit ctrl / break directly after powering up the router
Step 2: type: confreg 0x2142 from rommon 1>
Step 3: type: reset from rommon 2>
Step 4: Would you like to enter the initial configuration dialog? [yes/no]: answer NO
Step 5: type: en from router>
Step 6: type: COPY STARTUP-CONFIG RUNNING-CONFIG from router#>
Step 7: type: SHOW RUNNING-CONFIG from router#>
Step 8: type: CONFIGURE TERMINAL from router#> to remove any existing passwords enter Global Configuration
Step 9: type: NO ENABLE SECRET from router (config)#>
Step 10: type: NO ENABLE PASSWORD from router (config)#>
Step 11: type: CONFIG-REGISTER 0x2102 from router>
Step 12: Return to Privileged Exec by hitting the CTRL Z keys
Step 13: type: COPY RUNNING-CONFIG STARTUP-CONFIG from router>
Step 14: Reboot the device