What about killing youself afterwards?

Only if it's their first kill

The only thing that bugged me about Batman was the fact he didn't kill, like the amount of lives he could've saved if he just did a Deadpool and popped a bullet or two.

What if you kill all the killers and then yourself?
No more killers anywhere yay

Kill a man and you're a murderer; Kill a million and you're an Emperor.