I am still wondering why Barber felt a need to destroy the printed scores
of his Second Symphony, and why Schirmer's was willing to let him do it.
That was a very unusual act, I would say.  Andrew Schenck wrote in the
liner notes for his recording of this work that "the composer's own
explanation, that it is 'not a good work", remains frustrating and
unsatisfactory.'" Certainly Karl and Steve would agree with this, and I
would not disagree.  It might be that Barber's turning against the work
had something to do with memories and associations, rather than any lack
of success the work had or any clear-eyed critical view of it.  Richard
Whitehouse, in his notes to Alsop's recording, indicates that although
the work was "withdrawn" in 1964, the actual destruction was three years
later, i.e.  in 1967.  Clearly, for some reason(s) Barber not only did
not want the work played any more but, in attempting to destroy it--by
tearing it up with his own hands, as I imagine--he was violently
disassociating himself from it, and even expressing hostility to a work
he had made and which was part of his own past.  I never thought of
Barber as a political man, but I do recall first hand what 1967 was like:
it was the height of the Vietnam War, with rage in the air, and it is
just conceivable that Barber, who had written this work very much as
part of the "war effort" during WWII, wanted to dissociate himself from
the militarism his work represented.  Just speculation, to be sure, but
make no mistake about the original significance of that work; that is
made extremely clear in the Heyman bio.

More usually, when composers have withdawn or destroyed their own work,
it has been because they considered it inferior to mature work.  Hovhaness
destroyed vast numbers of early scores, and went on to write vast numbers
of later ones.  William Schuman withdrew his first Symphony, did he not?
An instance of a late work being destroyed is when Sibelius--most
likely--destroyed the score of a possibly complete 8th symphony, because
he knew his powers were much diminished--no doubt from too much drinking--
as nearly as I can infer from the most comprehensive biography of that
composer.  What other composers have famously destroyed their own works?

Jim Tobin