Video recorded by another passenger shows the man standing on a seat, kicking the cushion again and again and destroying the plastic tray table.
Gino Galofaro said he filmed the incident and then worked with others to restrain the man.
"I took that video really quick and I watched the flight attendant walk by and do nothing," Galofaro told ABC7. "Nobody on the plane was doing anything. So I got up and proceeded to restrain him. Two other bystanders were getting zip ties from the flight attendant. So we had to restrain him with zip ties and then seat belt him to the seat."
Galofaro is the founder of Hope Interventions, a Southern California organization that specializes in substance abuse recovery. He says he believes the unruly passenger was under the influence of drugs.
United says law enforcement met the plane upon its arrival at LAX. The passenger has been banned from all future flights on the airline.
The incident happened on United Flight 502 from Austin to LAX on Nov. 16.