It is possible to remove all of the content from a Lion Calendar server using Postgres. To aid you in doing so, Apple has built out a couple of commands to make the process easier. This will nuke everything from the server and so is not something that should be lightly done. To do so, first stop the Calendar service in the Server application. Then let’s back up the database: pg_dump -U _postgres caldav -c -f /db_backups/caldav.sql Then run dropdb to remove the database itself: dropdb -U _postgres caldav Once the database is gone, run the calendar_bootstrap_database script (I prefer doing so verbosely): calendarserver_bootstrap_database -v Now you should be able…