86

I first encountered the term "86" in the early 1960s.  I once went to Barney's Beanery, a famous low-rent joint in Hollywood. This dump had a sign behind the bar--I won't repeat the wording--that crudely informed customers that gay customers would not be served. About that time a known character actor saw the sign and told the server off. I did not witness this, but I heard later that the actor had been 86-ed. 

86-ing someone or something has several meanings, but the main meaning is that you are refusing service to somebody. You are banning somebody. 

None of the meanings imply violence. 

That 86 implies assassination is outrageous bullshit made up by Crybaby Trump. 

 "86" commonly means to discard, cancel, or refuse service to something or someone. Origins and uses:

• Restaurant/bar slang: to mark an item as sold out or to refuse service to a customer.
• General slang: to get rid of, remove, or cancel something (e.g., "86 the plan").
• Verb and noun: can be used as "to 86" (verb) or "an 86" (noun, meaning the person/item removed).

Possible origins (uncertain, several theories): shortened bartender jargon, rhyming slang, military codes, or menu numbering; no single proven source.