According to UrbanDictionary.com
"86'd
In the early days of the Remington and Royal typewriters, when paper was expensive and the results messy, overtyping to block out errors (e.g.: old prices on the daily menu or items out of stock) was common. Repeated typing
of the the digits 86 over a word would cover almost any previously typed word. The X was also used, and when you either typed "X" or "86" over a word the resulting edit was always called an "86" and anything so blotted out was "86'd". That's the connection with Delmonico's, and other downtown NYC eateries where the menus were printed for the day or week and had to be "overtyped" to eliminate items off the menu.
The raw oysters were 86'd by the time we got seated for dinner."
....... aaaaand a bunch of others
Anyone can post anything they want on that site.
Ever hear the reference you posted anywhere on this planet including the plethora of movies about Jimmy Hoffa, Mafia, Westerns, or even Batman as part of the 20-minute execution process of the day that the Joker had created for him and Robin and told him in excruciating detail what was going to happen and that it would end up with him getting 86'd?
Neither have I.
We both have heard the bar term though. The original restaurant one? Not so much, but that one's actually documented in printin the 1930s. Doesn't mean the term didn't exist prior to that, but the bottom line is, Trump is simply just not that old, let alone old enough to remember gunfighters at the OK Corral talking about doing it.