Was it kant, wittgenstein, heidegger, or nietzsche?
Philosophy is alive and well, thank you. You may, however, have a conception of philosophy, that does not fit in. But that is all right. You just have to think a little about it. After all, the question, what is a philosophy is a philosophical question. So by trying to answer it, you will get right into the swing.
By the way, I cannot refrain from remarking that your question, who destroyed philosophy? commits the elementary logical fallacy (noted by Aristotle, by the way) called, "the fallacy of many questions", for it supposes something that you have not shown is true, namely that philosophy has been destroyed. Sometimes this fallacy is also knows as the fallacy of begging the question. Just FYI.