EWR Area was a part of New York Tracon (N90). N90 was made up of 5 areas, Ewr, LGA, JFK, ISP, and Liberty. Ewr Area works EWR/TEB/MMU/CDW and all the uncontrolled fields in northern Nj (basically anything north of TTN).
The FAA’s reasoning (officially anyway) for the move was that long term to improve staffing, it had to be moved off Long Island. In fairness, I also have long advocated for that. Not enough people were willing to transfer to LI, and too many trainees came and quit cause they didn’t want to get stuck on LI. But they couldn’t have done it in a more slapstick haphazard way. Ripping a single area out of the building was not a solution. Relocating the whole Tracon to a more desirable location (something they had tried to do back in the early 2000’s before Schumer squashed it) would have been the proper answer.