How do I get rid of stress? Meditation or exercise?

Both are good. No one can get rid of stress completely. So it's important to learn how to manage stress. It boils down to avoid, alter, and adapt. In other words, avoid whatever stress you can and change what you can. If you can't do either of those then meditation and exercise are both good stress reducers when they're done regularly, ie, every day.
Exercise. Exercise helps stress reduction. I would not recommend medications even though benzodiazepines can have a calming effect. Yoga, lifestyle modifications help too.