want to uninstall ubuntu 12.10 which was installed through wubi

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http://askubuntu.com – i had installed ubuntu 12.04 LTS and later uninstalled it succesfully. Now again installed ubuntu 12.10 but i get messsage as "installer crashed" ,when reported it comes as third party items involved ,not official,so cant report :((( So i decided to uninstall it to start from first ,but after uninstalling also i get both ubuntu and windows options while switching on pc . please urgent help needed (HowTos)