How do I fire someone from a job ?

My boss wants me to fire this other guy I work with. The problem is I actually like this guy as a friend. Personally I have never had problems with him and I think he’s pretty good at what he does. We hang out after work too. The problem is – we both do the same thing. So if I were to tell my job not to fire him or ask him to tell the other guy himself, theres a chance that I can lose my job.

So how do I tell my friend that he has to leave his job in the nicest possible way ?