How to Deal with an Angry Child in Islam
Question

I have a son who is very hot tempered. How can I deal with this characteristic?
Praise be to Allah.How to deal with an angry child in Islam
Means of dealing with anger  include the following: 

Seeking refuge with Allah from the accursed devil .
Keeping quiet.
Calming down; if you are standing, you should sit down; if you are sitting, you should lie down.
Remembering the reward for restraining anger , as it says in an authentic prophetic narration: “Do not get angry and Paradise will be yours.”
Understanding the high status of one who controls himself, as it says in an authentic narration: “Whoever restrains his anger, Allah will cover his faults. Whoever controls his fury – even if he is able to show it – Allah will fill his heart with hope on the Day of Resurrection.” (Classed as sound by Al-Albani in Al-Silsilah Al-Sahihah, 906)
Learning the teachings of the Prophet (peace and blessings of Allah be upon him) concerning anger.
Knowing that controlling anger is one of the signs of piety, as it says in the Hadith quoted above.
Paying attention when reminded, controlling oneself and following advice.
Knowing the bad effects of anger.
Thinking about how one is affected at the moment of anger.
Praying that Allah will remove this resentment from one's heart.

Useful story on how to how to deal with angry child
There follows a lovely story which will help you to deal with angry children : 
There was a boy who was always losing his temper. His father gave him a bag full of nails and said to him, “My son, I want you to hammer a nail into our garden fence every time you need to direct your anger against something and you lose your temper.” 
So the son started to follow his father’s advice. On the first day he hammered in 37 nails, but getting the nails into the fence was not easy, so he started trying to control himself when he got angry. As the days went by, he was hammering in less nails, and within weeks he was able to control himself and was able to refrain from getting angry and from hammering nails. He came to his father and told him what he had achieved. His father was happy with his efforts and said to him: “Now, my son, you have to take out one nail for every day you do not get angry.” 
The son started to take out the nails for each day that he did not get angry, until there were no nails left in the fence. 
He came to his father and told him what he had achieved. His father took him to the fence and said, “My son, you have done well, but look at these holes in the fence. This fence will never be the same again.” Then he added: “When you say things in a state of anger, they leave marks like these holes on the hearts of others. You can stab a person and withdraw the knife but it doesn’t matter how many times you say ‘I’m sorry,’ because the wound will remain.
For more details, please see the following answers: 10016 , 270306 , 21390 , 215167 , and 88153 .
And Allah knows best.