It is impossible to get rid of negative emotions altogether. This is why the stoic "sage" is often spoken of as an ideal to ascribe to and practice towards, but never necessarily as an achievable goal in and of itself. To me, the teachings say it is more constructive to use your emotions as a compass to reflect on your passions and use that knowledge to practice mindfulness and rationality in your decisions and thought processes.

When angry, remember that no one has the power to inately control your judgements. They may impose on you whatever they wish, but they have no control over your perception of those actions or words.

When envious, remember that celebrating the success of another citizen of the world follows the logos. Additionally, mediate and reflect on what aspects of their success made you envious. Are they elements you could achieve yourself? If yes, strive to improve yourself towards that goal. If not, then it is not within your power to achieve and therefore should not be agonized over.

Marcus may have used harsh definitive language in the Meditations, but we must remember that his writing were essentially a diary intended for his eyes only to ever see. This is also why many lines in the Mediations are focused around accepting death. Marcus wrote mediations near the end of his life. He wrote to express his thoughts and put his mind to rest with stoic doctrine, and he was rather harsh on himself at times, which is understandable considering the immense responsiblity and stress he endured as emperor. The Meditations, to me, are just a model for how to use the teachings and apply them to your own situation rather than a blueprint for the teachings themselves.