I have a Q&D EXEC I wrote to remove old entries from SIGNUP FILE.
Mine had grown to over 16,000 entries, and I removed over 4,000.
My EXEC generates a file(SIGNOFF FILE) with a REG userid@nodeid OFF
for each user in the SIGNUP FILE who is not in a LIST.  You can then
send the file to LISTSERV, for it to unregister the people.  The
next IPL of Listserv will clense the SIGNUP FILE.  (I reccomend
sending no more than a couple hundred at a time, since my 4,000
took 5 hours to run, and caused Listserv to bomb with a storage
exceeded message)  If you are interested, drop me a line, requesting
LSVUNREG EXEC.
 
Harry