new monetdb version, old farm

Hello - My understanding is you should not run a new monetdb version with a dbfarm created from an older version. We have just updated our system from a Jul2015-SP3 version to the latest Jun2016-SP2 version. I have created a new db farm and plan to recreate the tables in the new farm. My question; How do you remove the old dbfarm? Our data is quite large (1.8 T) and I'd like to retrieve this space for other use. While I can start the db against the new farm, I can find no method of removing the old dbfarm to reclaim this space. Thanks - Lynn