How to remove all packages?

[Ray Phillips <r.phillips%uq.edu.au@localhost>]

I've tried to upgrade a NetBSD/amd64 5.0.1 machine which had the 
x11/kdebase3 package from a a couple of years ago installed to 
NetBSD/amd64 5.1 with x11/kdebase4-4.5.4 from the 2010Q4 package 
collection, but something has gone wrong and KDE doesn't work 
properly.

I'd now like to start from scratch as far as the packages go but 
without reinstalling NetBSD itself.  Will deleting these directories:

/usr/pkg
/var/db/pkg
/var/db/pkg.refcount

completely remove the packages that were installed and any reference to them?


Ray