I agree with lot of posters but there is one point I haven't seen addressed so far: do you expect this to be a surprise for him? If not, you've probably done so

I agree with lot of posters but there is one point I haven't seen addressed so far: do you expect this to be a surprise for him? If not, you've probably done something wrong. Were your expectations made clear to him? Since I have had to fire someone in the past (not a pleasant experience even if it went well), when I announced it, it wasn't really a surprise to him, his attitude was more "it's sad but fair". But it went that way because I had a few discussions earlier about what I was expecting in terms of actions and how what he was doing was not meeting these expectations. Also make sure he knows which things you don't really care for right now and find unnecessary right now. It is possible he is not delivering because he is putting more energy on things you don't care for. Creating this shared vision is one of the most important things you need to learn when managing employees.