Ask HN: Terminate an employee without feeling like a tool

I've got a few employees reporting to me in our product development team and for the first time I need to release someone. He is a little senior and has a family and kids. I've been putting it off because I feel bad about doing this. But his cost is high and doesn't justify his output. He's hardworking but simply not able to perform up to the expected standard.

How do you get yourself to pull the trigger?

(Throw away account for obvious reasons)