No, in the terms you chose: murder and simulation. A computer simulating a consciousness (a term whose definition we will restrict here to “apparently independent thinking”) is not a computer experiencing a human conscience. The latter does not exist yet but when it will be the case it will not be possible to give a computer scientist response because the programs will have nothing to do with those today. They will owe to their designers only what the personality of an adult human being owes to his genes. They will be just as self-organized, independent, responsible? The law has not yet thought about it.
On the other hand by choosing the term “murder” you plunge into a completely different level of the problem which is that of morality and its sociological rules. There are many cases on this planet of deliberate extinction of human consciousness that are not called “murders” in the context of war or excessively heinous acts committed by the consciousness in question. Another question that divides people: can we use the term murder in the case of a non-human conscience, animals for example? It touches the sacred of the species and poses difficulties to our moral sense.
So I would gladly answer yes to your modified question as well: “Turning off a computer experiencing an consciousness of the same order as the human conscience could it be considered a murder? “