If you want to clean up your Ubuntu or Debian machine and delete unnecessary (orphaned) deb packages you can use utility
deborphan. It finds packages that have no packages depending on them. The default operation is to search only within the libs and oldlibs sections to hunt down unused libraries.
If you’ve been reading debaday for a while, chances are you now have a heap of packages installed that you’ve tried out, some of which you want to keep installed, and some of which you have forgotten.