Pete Townshend of the Who regularly would smash his guitar on stage as part of his performance. Was he the first musician to destroy his instrument as part of a performance?
Not to the extent of actually destroying the instrument, but Jerry Lee Lewis was well-known for kicking the stool over, stamping on the keys, sitting or standing on the piano & generally mistreating it as part of his act.
Somewhat gentler times - that was probably seen as just as controversial; though it would be quite hard to swing a piano ;)
By the end of the 60's even smashing a guitar was no longer considered exciting enough. Hendrix even set fire to his.
Nam June Paik wrote "One for Violin Solo" in 1962.
The Lawrence Welk show from 1956 Features a fairly decisive guitar smash from "Rockin` Rocky Rockwell". https://www.youtube.com/watch?v=JQz0u2yV4Os&feature=player_detailpage#t=100
The fact he is not actually playing it makes me wonder if it qualifies as an instrument, or is more of a prop...
To a historical extent and certain verifiable records, Paganini and Liszt are also known to have broken their instruments while performing. Paganini was reported to have played on a violin that had only one string left, and Liszt might have broken a number of piano keys during his hectic performances. Now the problem is whether the decision to partially damage the instrument was deliberate in order to give off technical virtuosity and win over the audience.