Unfortunately, systemic change always takes violence, or at least the threat of violence. Every case where peaceful protest ever worked there was always a parallel violent movement. Any non-violent movement that gets anywhere close to real victory can also count on violence from the other side.
'Course, it is more effective the more directed the violence or threat thereof is. Just killing anyone who disagrees with you will only serve to make you enemies, target it at specific people that are a problem and you're more likely to gain supporters, as it's easier to justify than the wide-net method.
That is to say nothing about whether political violence itself is moral or not, I'm generally on the side of "until it's for anarchism forever, it's kinda amoral. I'd rather convince the people through words like a human, and then use violence as an absolute last resort against those unwilling to relinquish their positions of power, or those who attempt to 'fill the new power vacuum' they don't know has been filled by 'the people.'"