Anger is not a bad thing in itself. All human capacities are not inherently evil, but have become corrupted and disordered by sin. What then did God give us anger for?Anger is by nature designed for waging war with the demons and for struggling with every kind of sinful pleasure. Therefore angels, arousing spiritual pleasure in us and giving us to taste its blessedness, incline us to direct our anger against the demons. But the demons, enticing us towards worldly lusts, make us use anger to fight with men, which is against nature, so that the mind, thus stupefied and darkened, should become a traitor to virtues. -Abba Evagrius the Monk
When you struggle against sin and the inflamed passions of your fallen heart and mind, it is not only okay, but has been considered essential by the spiritual fathers of the Church throughout the ages that you use your capacity for anger to violently push out all thoughts of sin from your mind. As our Lord said, «The Kingdom of Heaven suffers violence, and the violent take it by force.» This is not an exhortation to physical violence, but in all matters of spiritual warfare against temptation, to violently seize your salvation by force from those who would steal it away.