As far as I’m concerned (and I’m far from the authority here) any person can call themselves a witch, its just a matter of being able to back it up when someone challenges you.

To add to this, every witch from every tradition is going to have different standards of what a witch is and isn’t according to them, and you’re not going to be able to impress everyone.To those you do impress, you’re a witch. To those you don’t, you’re a pretender. But what really matters is not their opinion, but yours and your magick’s.