I do manage to keep my self calm at times. But lately i feel i can't control the bubbling anger within me. I keep lashing out over small things. Sometimes even the smallest things can annoy me. I have tried breathing techniques and i must say that they are very useful in keeping self in check but it makes me very restless or like being sap out of energy. If anyone can give me advice i be grateful for it.
The calmness of a lake in the morning is buffeted by the afternoon wind. Serenity lies deeper, below the angry winds:
To let go of anger, stop holding the honey tip.
To let go of the honey tip:
MN62:3.2: “Rāhula, you should truly see any kind of form at all—past, future, or present; internal or external; coarse or fine; inferior or superior; far or near: all form—with right understanding: ‘This is not mine, I am not this, this is not my self.’”
That is not easy, but give it time, space and diligence.
Keeping yourself calm is clinging to an illusion of control of what comes up in your mind. Nobody can do that. It's like there is no way that after reading "don't think of a white rabbit" you can stop yourself of thinking of one.
Instead, try to observe the emotion/thought arising in your mind and just let it happen without judgment or attaching other thoughts to that arising. You will "see" that it's generally not the initial emotion arising that makes you lash out, but secondary thoughts you attach to this "train of thought".
Try to just let the initial "locomotive" arise and dissipate without judging yourself for lack of control. Control over thought is an illusion.
The purpose of meditation is not to "stop thinking" but to learn to see that there are spaces between arising thoughts, and to make the duration of those spaces longer by experiencing that thought is not a constant "stream" but more like a "dripping tap". It is only when you attach thoughts to the initial one that you open the "floodline".
Hope this helps.
Adding to the good answers that have already been provided, I would just like to say that sometimes you have to stop clamping down your anger and start trying to understand why you feel what you feel. Don't shy away from it, don't judge it, don't be angry with it. Try to understand it. Why is there anger bubbling inside you? Are you really angry at the small things that cause you to lash out, or is it a symptom of a deeper problem?
It's OK to be angry, it's normal, everybody feels it. Nobody likes it, of course, but that does not mean that you should block it and pay no heed to it. That will only be worse in the long run.
The quickest way to tranquility is to stop fighting against your own feelings, accept and understand them, without judgment or fear. Indeed, how can you be tranquil and peaceful if you are at odds with what's happening inside you? Remember annata, you are neither your thoughts nor your feelings. From SN 22.59:
"Form, monks, is not self... Feeling is not self... Perception is not self... Mental fabrications are not self... Consciousness is not self..."
Feelings come and go as they will, change and morph from one state to another, so don't be afraid and upset when they are unpleasant, or they are not "what they should be". The problem is not the anger: as @Codosaur said, the lashing out part is caused by the "secondary thoughts", by the judging that happens with (and towards) that anger.
Of course, I'm not saying that you should let your feelings run wild and exercise no self control, far from it. Be heedful of your behaviour, while it's ok to be angry, it's not ok to lash out and hurt other. But you should definitely sit down and try to work out what's happening with you, with an honest, kind and non-judgmental mindset towards yourself.