I wouldn't even attempt to clean it.. just install a new build of Ubuntu, replacing
the old.
I scrapped Ubuntu and went with Linux Mint 16 Petra
http://blog.linuxmint.com/?p=2493 64
bit instead. I could no longer stand Ubuntu's stupid desktop environment. If
you're installing 64 bit, make sure you have at least 4 gb of ram. gnuradio won't
compile with less.
Also, prior to installing Pybombs, you need to manually install an audio dependency. See
this post
http://forums.radioreference.com/software-defined-radio/282056-sdrs-vs-hard…
I made over on the RadioReference forums.
-Scott