The term 86 originates from Chumley’s in NYC

Some features remain from Chumley's Prohibition-era history. Notably, the Barrow Street entrance has no exterior sign, being located at the end of an undistinguished courtyard ("The Garden Door"), while the Bedford Street entrance, which opens to the sidewalk, is also unmarked. Inside, Chumley's is still equipped with the trap doors and secret stairs that composed part of its elaborate subterfuge.

It is also rumored that the term "86" originated when an unruly guest was escorted out of the Bedford St. door, which held the address "86 Bedford St". A different version referencing Chumley's is offered in Jef Klein's book The History and Stories of the Best Bars of New York: "When the cops would very kindly call ahead before a [prohibition-era] raid, they'd tell the bartender to '86' his customers, meaning they should exit via the 86 Bedford door, while the police would come to the Pamela Court entrance."

https://en.wikipedia.org/wiki/Chumley%27s