Airbus Group NV said on Tuesday it has terminated an agreement to deliver six A380 superjumbo jets to Skymark Airlines Inc after the Japanese discount carrier struggled to raise enough cash to pay installments on the aircraft. In a briefing in Tokyo before Airbus’s announcement, Skymark’s CEO and chief investor, Shinichi Nishikubo, said that the European aircraft maker had refused to consider changes to the 2011 purchase agreement, including reducing the number of aircraft or offering smaller jets and had notified it of the termination in a faxed message on Sunday.