As I am unsure of your ability, I cannot really say what you personally can and can't do, however I will attempt to give you general ideas of it.
First, you can look for another job. Yes, it's not easy to find a job in this economy blah blah, but if you are really wanting out of the situation, you can leave and find something comparable. This hinges on your ability to wait it out and keep your mouth shut about your boss and wanting to leave.
Second, you can stop worrying about your boss being impossible and live with it. Sometimes the best response is to just shrug and go with the flow. Unless they are doing something illegal or unfair, I would take this route first.
Third, if it is something illegal or unfair, you should contact your boss's boss or your human resources manager. If you do not have either of these, you will want to look into a general human resources manager or into a lawyer. You need to protect yourself from people who would abuse your position and you.
If you really wish to do a spell to rid yourself of your boss, you should do something simple, such as a spell using candles and a piece of paper, writing your wish (for your boss to not be around anymore) on the paper and burning it with the use of the candle. If you take this or any other magical route, be sure that you are specific, as "I want rid of my boss" means anything from a promotion, a firing, or death. Words and intentions are important in magical practice, and as a practitioner you would do well to take note of this.