Complex sentence: In June 1984, Kantner left Jefferson Starship, complaining that the band had become too commercial and strayed too far from its countercultural roots; at the time, he was the only remaining original member of Jefferson Airplane in the group.
Split into simpler sentences: In June 1984, Kantner left Jefferson Starship, complaining that the band had become too commercial and strayed too far from its countercultural roots. At the time, he was the only remaining original member of Jefferson Airplane in the group.