There are a number of reason why an old building, like this Old-Law tenement, might have its stoop removed. The most common is that the sidewalk was narrowed to widen the driving lanes of the street, and the stoop took up too much of the new sidewalk. That might be true here, but it doesn’t look like it is. The old door at the top of the stoop has been removed, but there’s no new door at the basement level, at the sidewalk, which only makes sense if this building was combined with one of its neighbors (in this case, to the right or behind) or if the gate on the left leads to a new side entrance.
But what caught my eye is that the old main door was bricked in rather than being converted to a window. Windows that don’t lead to airshafts are precious in these tenements, so it’s surprising that the door was filled in like that. It took me a minute to remember what it reminded me of, but I doubt that anyone was bricked up behind it.