I have a bunch of files that have been backed up in one directory on this
node that we no longer need to keep.  These files all have unique names,
but share the extension of .prt.  There is a very large number of inactive
versions (simply because these are temporary files that get deleted each
day).  I would like to find a way to expire the files in this folder.

Is there a command to do this? or do I have to change the management class
for this file to a dummy management class/backup copy group (say, "nohold"
set to 1, 0, 0, 0)?

If I have to change the management class, what are the steps I need to do
to accomplish this?  Is it simply...

Create new management class/backup copy group (call it nohold)?
modify the options file for this node to have an "include <path>\*.prt
nohold"
and then run an incremental

Is that basically it?