Sayyidi wa sanadi Hazrat Mufti Mohammad Taqi Usmani sahib db said;
It is grossly inappropriate to display anger.
Anger is one of the first things to be treated in Tasawwuf and tariqat.
It destroys the batin (spirituality) of an individual completely.
Therefore, anyone who starts on path of islah (self reformation) and approaches a Sheikh for this, the first instructions are to cure anger. That is, he is able to control the display of anger. 
“For this, initially he is instructed not to display anger at all.
That is, neither displaying anger at occasion where it is appropriate nor at times where it is inappropriate. Even, not displaying it when he has the right to do so. This attitude has to continue till he becomes emotionally balanced. (Sheikh will inform when this happens.)
In mean time if by chance he slips and displays anger using inappropriate words etc., he has to ask forgiveness explicitly from the one he became angry at. That is, to say, ‘brother, I said such and such. I made a mistake. Forgive me.’