Wayne LaPierre resigned as leader of the National Rifle Association on Friday, ending a long career during which the NRA became one of the most powerful lobbies in Washington, only to see its prestige tarnished by corruption allegations and a bankruptcy filing. LaPierre, 74, chief executive since 1991, steps down just as New York state Attorney General Letitia James brings a corruption trial against the NRA, due to begin in state Supreme Court on Monday. James had been seeking LaPierre’s removal from office, but he is still among four individual defendants in the case and is expected to testify.