Answered by Sayyidi Habib Umar bin Hafiz (may Allah preserve him and benefit us by him).
How can we overcome our anger?
You can do this through knowledge and action.
Knowledge is to remember the reward that Allah has promised to those who overcome their anger and those who show forbearance and to remember that venting one’s anger distances you from Allah. Remember that by controlling your anger you save yourself from the anger of Allah. Remember if you cannot control your anger you expose yourself to problems in this life and punishment in the next life. By controlling your anger you emulate the Prophets and the pious and by failing to do so you emulate foolish people and devils.
As for action, when you become angry, sit if you were standing and recline or lie down if you were sitting. Also make wudu or ghusl. Do good to the person who has angered you or wronged you. Seek refuge in Allah from the Devil and make the following supplication which the Prophet taught Sayyidah Aishah:
اللَّهُمَّ رَبَّ مُحَمَّدٍ اغْفِرْ لي ذَنْبِي و أَذْهِبْ غَيْظَ قَلْبيْ وأَجِرْنِي مِنْ مُضِلَّاتِ الفِتَن
Allahumma rabba Muhammadin ighfir li dhanbi wa adhhib ghayza qalbi wa ajirni min mudillati-l-fitan
“O Allah, Lord of Muhammad, forgive my sins, remove anger from my heart and save me from tribulations which send people astray.”
If you are sincere in seeking to control your anger you will naturally become forbearing.