"…lovingkindness—maitri—toward ourselves doesn’t mean getting rid of anything. Maitri means that we can still be crazy, we can still be angry. We can still be timid or jealous or full of feelings of unworthiness. Meditation practice isn’t about trying to throw ourselves away and become something better. It’s about befriending who we are already. The ground of practice is you or me or whoever we are right now, just as we are. That’s what we come to know with tremendous curiosity and interest."Related: In the book Good Life: A Zen Precepts Retreat with Cheri Huber, Cheri discusses why the Precepts (at least, the version that's used at the Zen Monastery Peace Center) state the relevant Precept as "not to be angry", not "not to get angry". (Paraphrased from recollection of what's in the book; it's been a while since I've read it.)
— Pema Chodron
Also, from Lovingkindness: The Revolutionary Art of Happiness by Sharon Salzberg:
Buddhism doesn’t teach that we should ignore or repress our anger; in fact it teaches the opposite. When we start to get angry we should turn toward it, study it fearlessly and come to know it as well as we can. The theory, like pretty much everything else in Buddhism, is that this willingness to know ourselves expands our freedom of movement. It lets us choose our path of action, harnessing the energy of anger without being driven mindlessly along by it.
This is an important skill to learn, because anger will always be with us. No matter how far we advance in the spiritual journey, it’s not too likely that we’ll wake up one day as saints, miraculously immune to the slings and arrows of outrageous outrage. In fact one of the best of the current candidates for sainthood, the Dalai Lama himself, was asked in a conference whether or not he ever got angry. He responded as though he’d been asked whether or not he still got hungry or thirsty: "Of course", he said. "If something happens and I don’t like it, if it is not what I want to have happen, anger arises."