Yes---turn it off, then back on while CONSOLEd into the router. When it is turned back on, initiate a break (ctrl-break, or whatever it is for your term emulator). When it gets to rommon, just do this
When it resets, answer "no" to "do you want to configure blablabla?" or whatever the exact wording is...then it will say "Press RETURN to get started!"---when you get to router>, just do this...
"Are you sure"...whatever it says---answer "y"
You should not have to do "erase start", since after you change the config register back to 2102, and after that you do a "wr" with no other config changes, you are over writing NVRAM, esentially resetting it to factory defaults, except without a password (Cisco routers new come with an IP address of like 10.10.10.1 and a default password). HOWEVER, I always do "erase start" for kicks, good measure. I am a backup plan type man.
tim@tim-laptop ~ $ sudo apt-get install windows
Reading package lists... Done
Building dependency tree
Reading state information... Done
E: Couldn't find package windows...Thank Goodness!