Jeffrey C. Barton had been scheduled for trial next week on the misdemeanor, The Columbian reported.
Barton will instead face a charge of obstructing a police officer, Clark County Prosecutor Tony Golik said Tuesday.
Barton, 53, acknowledges firing the gun in July 2013 to chase away three men who appeared to be breaking into his vehicles in Vancouver.
He planned the so-called "Biden defense," based on a statement the vice president made in February 2013 that people don't need automatic weapons because shooting a shotgun in the air would scare off intruders.
Golik doubts a jury would be persuaded beyond a reasonable doubt that Barton violated the law.
"A person, even in a no-shooting zone, still has the right to defend their person or their property," Golik said. "In this case, based on the facts, there is a reasonable argument that Mr. Barton may have been defending his person and property when he fired in the air."
Barton said the obstruction charge also is groundless.
"Tony Golik is desperately grasping at straws" to keep out of a civil suit, Barton said. "They have to charge me with something; they've let this go on too long."
His trial is tentatively scheduled for Oct. 24.