[ubuntu] How do I uninstall 12.10

Hi, I dont like version 12.10 and want to go back to ver 11.04. I have 12.04 installed with the windows installer taking 12 gb of my 40 gb drive.
I know how to install 11.04 but I am not sure how to properly (and completely) uninstall 12.10.
there is the wubi that I installed it with, It has an uninstall option, maybe that's it? I dunno.
Thanks in advance!):P