Anger: an emotional response to being or feeling threatened. The body kicks into a flight or fight response when we feel threatened. 
If you know me, you know that I am pretty level-headed most of the time, but I do get angry. I might even yell at my kids from time to time and get frustrated when driving. I have had people say things about angry yogis as if we are not supposed to have what are perceived by our society as negative emotions-fear, anger, envy, jealousy, frustration. 

One thing is certain and that is that I have less anger when I am doing my practice regularly and when it’s the right practice for me. Most importantly I meditate and keep gratitude in the fore front of my mind. I also need to take care of my human needs-food, sleep, exercise. 

Is it okay to express anger when your a yogi? Of course! As with most things, there are appropriate ways to let off steam, and anger is energy, heat energy. With time, anger, like heat, will naturally dissipate. Guilt for feeling anger does not help the situation. One thing we can do is to observe and be mindful of those situations, people and places that affect us and decide if and how we will do them in the future. 

Causes: Some of the main causes of anger are that we don’t get what we want; we’re afraid we’ll lose something we have; patterns (samskaras); driving; relationships; it’s hot outside; we didn’t sleep well last night; our diet sucks; we make other poor health choices, etc.

What can you do? 

Meditate regularly
Count to 10
Talk to someone
Take a walk in nature
Listen to calming music
Take Action 
Do appropriate asana for our body type, climate and age 
Follow our routines that support a healthy lifestyle

Prevention is key–being proactive can help avoid many situations that could lead us into blowing our top. Taking care of our health is the first step. Also, doing what we need to do so stress and frustration don’t overtake our lives, avoiding dangerous relationships, procrastination, and other things that trigger our anger. Following guidelines and routines for our dosha, season, and ability are also helpful.
If you have other ideas, please share them.