You can use the 'autoremove' action. As mYself pointed out, it is a simpler
solution. However, 'autoremove' is kind of dangerous. It removes the packages
that were installed as dependencies.
For instance, Trisquel's default system actually is installed through the
metapackages "trisquel" and "trisquel-recommended". If a user removes an
application in the default system, she removes as well one or both of those
metapackages. Then, 'autoremove' actually suggests to remove everything since
the rest of the system was installed as dependencies of those two
metapackages. That is certainly not desirable.
The method I suggested (seeking in the logs the dependencies that were
installed along "triskel" and "triskel-recommended" and removing only those
packages) is safer.
