It was apparently removed due to redevelopment, and the pump is not the original anyway. Given they later reinstated the memorial, this isn't quite the act of historical vandalism it may first appear.
I'm not 100% sure, but I don't think it's run by the same people as it was back then. It just stuck in my mind a particularly nasty thing to do so I never went back.
> There is a plaque and a [water] pump, and the John Snow pub opposite
The plaque and pump were removed several years ago, much to my dismay as an amateur London tour guide.
The pump was then reinstated in 2018 but it was still jaw dropping that such a landmark was removed in the first place.
https://lookup.london/john-snow-water-pump/
Quite interesting