Now that PT4 for Mac is out, I don't have any need for PT3. How do I go about deleting PT3 and its loose ends, but more importantly, how do I delete the PT3 DB? (I'm not importing my PT3 DB to PT4, so I just want to get rid of it.)
The easiest thing to do is to go into PT3 and create a new database and set it active and default. Restart PT3 then go into Database --> Database Management and delete the old database. You'll be left with a single empty PT3 database lying around but that'll be pretty trivial in terms of size - and you'll be keeping PostgreSQL around for PT4 anyway so you won't want to remove that entirely.