Howtogeek posted a tutorial about removing Ubuntu One from Ubuntu 10.04

One of the new additions to Ubuntu 10.04 is the file syncing service Ubuntu One. If you already use a similar service like Dropbox, or you don't want to sync files between computers, you might want to remove Ubuntu One we'll show you how.
If you've never tried Ubuntu One, then the first two steps will be unnecessary, but they don?t take long so it might be safer to go through them all anyway.

  Remove Ubuntu One from Ubuntu 10.04