The manual instructions are here:
  http://www.lsoft.com/manuals/1.8d/qs/editlogs.html

However, as we've just learned the hard way, be aware that you cannot edit
your active log file. If you do, your list will be held as soon as the new
log file reaches the same size as the deleted one. You must wait until a
new one is up.

The good news: Whether you're on weekly or monthly, that is soon.

The latest issue of WOW (Woody's Office Watch) is all about the Klez virus.
You can find it here:
   http://www.wopr.com/wow/wow.htm

HTH.

Cheers,
Deborah Shaw