Can a person get rid of anger permanently simply by letting it out or is forgiveness necessary to be rid of anger?
The answer depends on the level of injustice and the depth of the anger. If the other was insensitive without being cruel, then your expressing an appropriate, measured level of anger may take care of the issue. On the other hand, if you have been treated very unfairly and your anger is deep, then catharsis (letting out the anger) may not be effective. Forgiveness then may be required to rid yourself of the anger. Please keep in mind that catharsis by itself, when the problem is serious and the anger is deep, actually can increase the anger and lead to a pattern of being angry and expressing it. Catharsis then needs forgiveness to deal in a healthy way with the anger.
Learn more at How to Forgive.