a non-Christian POV:
I think God has the right to kill, but I don’t think he can maliciously kill. He has the right to kill bad persons. But he doesn’t do it maliciously or, perhaps better put, with any merely human “wrath” or vindictiveness. He kills simply because it’s sometimes the necessary thing to do, the thing that must be done out of duty.
I know Catholic and other Christian apologists sometimes say that God does not have human emotions, but when the Bible talks about God being “angry” and “filling the cup of his wrath” and whatnot, it’s hard to imagine what is being described besides some sort of hatred on God’s part. This I part ways with, since anger and judgment seem to be the purview of the human. IF God gets angry it’s only for a good purpose (maintaining order, say), not “an eye for an eye” or simple retribution.