how to delete Jetpack when the update failed?

Hi Auttomatic,
I tried to update Jetpack, but failed and it is now disabled. The plugin update-page claims that there are no files left, but when i tried to reinstall that failed too because the files are still there. How can I delete the files so I can make a clean install of Jetpack.
Kind regards
Elisabeth
http://www.electriccafe.dk

http://wordpress.org/extend/plugins/jetpack/