Wikipedia says it exists in hospitality sectors, meaning simply to eject something or someone, but it specifically refers to putting someone 6 feet under, which is explicitly murder.

Wikipedia says some slang dictionaries make the claim it refers to a grave but that is not the primary use or agreed upon origin:

Eighty-six or 86 is American English slang used primarily in the hospitality industry and sometimes in the military.

In the hospitality industry, it is used to indicate that an item is no longer available, traditionally from a food or drinks establishment, or referring to a person or people who are not welcome on the premises. Its etymology is unknown, but the term seems to have been coined in the 1920s or 1930s.

Military personnel might use "86" informally to refer to scrapping equipment (e.g., "That old radio got 86'd") or ending a plan or mission (e.g., "The op was 86'd due to bad weather"). It's not an official term in military doctrine or manuals, but it's part of the informal jargon that soldiers, sailors, or airmen might pick up and use, influenced by broader civilian language.

It does not and has never explicitly referred to murder. That’s just not true.

I mean the POS device literally had the button and the numbers appeared on the ticket at the chain restaurant where I worked