From: http://alpine.x10host.com/alpine/info/DelText.html
Upstream: constitutes upstream source, delivered in non-tarball form

This patch allows Pico and Alpine to remove all text of the message from the
position of the cursor up to the end of the file or message. All you need to do
is to press ^W ^X. If your signature is delimited by the string "-- " (two
dashes and a space), it will not be erased by this command.