What about planting a bomb in his building but "hoping" that he survives?

Since the idea right now is pretty basic, you could discuss that you still have the thought of killing him. 

I would approach it, by deteriorating the building. Start destroying outer parts of the building, maybe cut light/watter supply, so that the building becomes unsafe and the best option is to demolish it.
You would potentially have to raise a generation without telling them what is inside the building, so that they don't get any bad thoughts...