How can I become a Witch without anyone else knowing?

Don’t tell anyone. During the burning times, practitioners went underground, and so much knowledge was lost due to the secrecy involved, out of necessity. There is a strong movement in the pagan, wiccan community to “come out of the closet” so to speak, and be publicly proud of our ideas and belief systems, but this isn’t for everyone, and you have a right to your privacy.