That option was there until Patch 4 (or 3? not sure now) ... where "combat" button was removed from Bottom Left Corner ...
I never understanded why.
Its true you still can attack him, but only if you have another team member that attack him for you, while your character is locked in conversation.
Or only after you talk to him and after you are kinda forced to accept his apology. -_-
One of 10 worse decisions i have seen so far. :-/
