sudo apt-get remove --purge virtualbox-4.0
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages will be REMOVED:
  virtualbox-4.0*
0 upgraded, 0 newly installed, 1 to remove and 0 not upgraded.
After this operation, 111MB disk space will be freed.
Do you want to continue [Y/n]? y
(Reading database ... 50291 files and directories currently installed.)
Removing virtualbox-4.0 ...
Purging configuration files for virtualbox-4.0 ...
dpkg: warning: while removing virtualbox-4.0, directory '/usr/share/icons/hicolor/20x20/mimetypes' not empty so not removed.
dpkg: warning: while removing virtualbox-4.0, directory '/usr/share/icons/hicolor/20x20' not empty so not removed.
Processing triggers for hicolor-icon-theme ...
Processing triggers for shared-mime-info ...
Processing triggers for ureadahead ...