v. To reduce in number rapidly.
2002
Tell North Korea, a danger to Asian stability, that you won't come to its rescue as your grandfathers did if our bombers must de-proliferate its nukes.
1985 (earliest)
While many of the company managers have been saying that the industry must "de-proliferate" if it's ever to become a sound business, just the opposite is happening. Seventy-six different domestic cars have marched into the nation's dealerships for calender [sic] 1985, compared with only 69 cars in '84.
The verb to proliferate is often used when referring to increasing stockpiles of nuclear weapons, so it's not surprising to see the opposite term used in the context of reducing nuclear weapons. What is surprising is that de-proliferate originated not within the nuke community, but within the jargon-festooned minds of the automotive industry, where it means "to reduce the number of car models offered by a manufacturer." (More generally, other marketing types use the word when referring to a reduction in the number of brands a company offers.)