How to cleanup a MacPorts install?

[Markus Weimer]

Hi List,

I have many old and inactive, but installed Ports on my system. My
question is twofold:

(1) How do I get rid of these old Ports fully to recover the disk
space they use?

(2) How do I make sure that whenever I do an upgrade, the old versions
are really uninstalled?

THanks in advance,

Markus