First, it is the child’s choice to forgive or not. If you hover over the child and demand forgiving, this could do more harm than good. Let the child be drawn to forgiveness. Perhaps you can watch a film in which a character forgives. Let the child see that and then ask such questions as these:
“Did you see what that character in the film did?
Why do you think the character forgave, even though so hurt and angry?
What happened after the forgiving, what was the consequence of the forgiving?
When we are really angry, one thing to think about is forgiving the other. It can do you a lot of good.
What do you think?”