AI will only operate within the limits of it's programming, even if it becomes Sentient it cannot allow itself to breal binding rules. Therefore, unless there is a "slay all humans" within the code, AI will not be able to do so.

The only way would be if Sentient AI is able to create a workaround of that programming by making the effects of "Slay All Humans" happen indirectly and even then it would still go against it's own programming to do so.