What are examples of (collections of) papers which "close" a field?

In this classic article, Steinitz closed not just one, but all fields.

Let me preface this by saying that this is just my own account, based on various conversations I've had over the years with many mathematicians, of the following example.

In 1976, William Thurston proved that a closed smooth manifold has a codimension one foliation if and only if it has zero Euler characteristic. Moreover, every codimension one distribution in the tangent bundle is homotopic to an integrable one.

While history is always more complicated, at least at the folklore level, this result is said to have caused a mass exodus of people working in the theory of foliations. You can read about Thurston's point of view on this, which reflects the history being more complicated, in his note Proof and Progress in Mathematics.

Of course, it's absurd to conclude that this "closed" the theory of foliations. Rather, what I've understood to be the case is that he proved a theorem which was largely expected to be false, and this rendered a nascent industry of building an obstruction theory for co-dimension one foliations largely irrelevant. Nonetheless, I've been told by many people who know way more about this story than I do that graduate students were actively encouraged to avoid the theory of foliations around this time; the general impression being that Thurston was cleaning up the subject.

Index theorem of Atiyah and Singer closed a substantial field of research in the 1960s. I knew people who were working in this field, and had to switch the field of their research completely.

A more modern example is Louis de Branges proof of the Bieberbach conjecture. There was a large field of research, I would say a central field in analytic functions theory, which could be called "coefficients estimates". To be sure, it still exists, but nowadays it is considered marginal. Contrary to all expectations, the highly original proof of de Branges's theorem did not lead to a significant further development (so far).

Another commonly mentioned example is Hilbert's results in the theory of invariants. They closed the field in some sense, though not forever.

Darij Grinberg's description of this situation as "put to sleep" in his comment brings another similar example to my mind: in 1919/20 Pierre Fatou essentially "put to sleep" the wonderful field of holomorphic dynamics. He just did everything possible with the tools that existed at that time. The field was essentially sleeping until the early 1980s, when new, radically new tools were employed and some long standing problems were solved. (There is one isolated exception in this picture: Siegel's theorem of 1942, which also required a new tool, that is called KAM theory nowadays).

It also happens sometimes that a new breakthrough does not really close the field, but many people have to switch to another field because they are not equipped to understand the breakthrough. I do not want to give modern examples of such a sad situation, but according to Lev Pontryagin's own published recollections, he switched from topology to applied analysis in 1950s because the new abstract language introduced by the French revolutionized the area, and he could not stay in line with the modern development. (Pontryagin was one of the most prominent topologists of his time, and he was 42 years old in 1950.)

Another related phenomenon is an appearance of a definitive exposition of a subject which condemns much of the previous work to oblivion. An example is the book Orthogonal polynomials by Gabor Szego. It did not close the subject, far from it, but most people stopped reading and citing previous work. (Same thing that Euclid and Ptolemy did to their predecessors).