Dreaming that you are a witch or warlock or can cast spells can mean:
You're feeling powerless somehow in your life
There's a particular situation in which you'd like to have more power
You're having trouble accepting or dealing with reality or a certain situation
You'd like to have more freedom or autonomy in your life
For more clues, consider the type of witch you are and the type of power you have in the dream. For example, dreaming that you can control people or situation may mean you feel powerless, or perhaps you're feeling arrogant by thinking you know what's best or what should happen. Dreaming that a witch is after you can mean you're feeling victimized or manipulated somehow. Someone accusing you of being a witch can mean you're feeling falsely blamed, or afraid you will be.