To remove, end usage, or take something out or away. Despite ALL other posts suggestion the origion of this phrase there is only one true answer:
Chumley's, a famous and OLD New York speakeasy, is located at 86 Bedford St. During Prohibition, an enterance through an interior adjoing courtyard was used, as it provided privacy and discretion for customers.
As was (and is) a New York tradition, the cops were on the payroll of the bar and would
give a ring to the bar that they were coming for a raid. The bartender would then give the command "86 everybody!", which meant that everyone should
hightail it out the 86 Bedford enterance because the cops were coming in through the courtyard door.