This is the very antithesis of Sattva, represented by the Brahmins. In our Yoga Sadhana we should never forget that a certain amount of destruction is absolutely necessary. Unless we destroy the weeds, the beautiful crops will not grow. Unless we annihilate our bestial nature and sublimate the human nature, we cannot rise into our divine nature. Just as righteous kings are as essential to the world as pious Brahmins, Rajas properly directed and canalised is as important to Sadhana as Sattva.
Unrighteous kings can cause havoc.
Rajas mixed with Tamas not only veils the Atman but makes man stray into the lethal chamber of lust, anger and greed. This must be completely rooted out, if we are to progress towards establishment in Sattva. In order to avenge this, Parasurama kills the kings. He thinks his father would be pleased with his conduct, but he finds a different attitude in his father. You are a Brahmin, and the foremost duties of a Brahmin are forbearance and forgiveness.