I love releasing anger with a wiffle bat on a pillow or some such. Something that makes a real satisfying sound. I don't think it can hurt you, unless you're on the ropes with your superego, about your anger. And then anger/strength in dealing with the Inner Bully is also the correct response. I think the psychotherapy world has often asked this question ellie, and no great conclusions can be drawn. If it feels good, I say do it. Why not? If it is agitating, don't.
The skilled means of doing it is to physically feel the energy of release in your body, and not get caught that the object of your beating will actually "respond" to your expression. It is all about "energy" and about our own feeling of aliveness in our bodies that can provide support to "be ourselves" more fully. Sometimes in dancing I can feel so strong and muscular, and this is satisfying. This is what "beating the pillow" can give you access to. Or not.