UNIONDALE, New York — Ringling Bros. and Barnum & Bailey Circus folded up its Big Top for the last time on Sunday night in New York, as emotional performers, wistful crowd-goers and ecstatic protesters said farewell to an institution in American live entertainment after nearly a century and a half. The circus gave the final performance of "The Greatest Show on Earth" to a sold-out crowd at Nassau Coliseum, showing off its death-defying stunts and exotic animals for the last time after 146 years.