delete items from summary, not from mail server?

[Joe Corneli <holtzermann17@gmail.com>]

Wanderlust decided to download all of the mail summaries, but it
appended this information at the bottom of the summary buffer, when
there were already quite a few items there previously.  Is there a
good way to permanently delete items from the local summary buffer,
but not from the mail server?  I just think it would be nice to start
with the message number "1" at the top of this buffer (now that I have
it!).