NEW YORK, Oct 7 (Reuters) - Puerto Rico bond insurer Assured Guaranty Ltd said late on Friday it voluntarily withdrew a complaint that challenged the legality of the island's fiscal turnaround plan, citing the devastating impact of Hurricane Maria. The move may temporarily ease Puerto Rico's financial problems as it struggles to get back on its feet after Maria hit last month, destroying the electrical grid and leaving most of the island's 3.4 million inhabitants without power. Assured Guaranty, along with a second insurer MBIA Inc, filed their lawsuit against the island's government and a federally appointed financial oversight board on May 3, a day after Puerto Rico announced a historic restructuring of its public debt.