“86” means “get rid of”, not kill.

https://www.7shifts.com/blog/what-does-86-mean-hospitality/

"The term 86 is used throughout many different industries, but is mostly associated with the restaurant, bar, and hospitality industry. While the etymology of the term 86 has a few different stories, there are multiple theories around where this term originated from. In nearly every context, it means to “refuse service”, “get rid of” or “nix” something.

According to Merriam-Webster, the origin of the term 86 began as a slang term that meant something was sold out at soda bars in the 1930’s. This term was thought to have come from the rhyming slang term “nix”, which is to cancel something.

During the Prohibition Era, a speakeasy called Chumley’s bar was located at 86 Bedford Street, Greenwich Village, New York City. Police showed up at the hidden bar to shut it down, and apparently told patrons to “86” (leave) the area by using the secret back door that led to 86th Bedford Street. Which was different from the main entrance that police would use on Barrow Street.

Other possible origins of where the term 86 comes from is also tied to bars and alcohol. Prior to the 1980s, whiskey was available as 100 of 86 proof. When patrons drank too much of the 100-proof whiskey, they would become belligerent, and the bartender would have to “86” them, meaning they would have to switch to 86-proof liquor or leave the bar if they were unruly."