Cutting off body parts to treat body dysphoria is something that should be done with great care and rarely leads to solving the underlying mental problems.
Trans is a much discussed variant that is hard to have a normal talk about, but there are many more variants, for instance women hating their breast & wanting to remove them, I think most people here would agree that intensive psychological treatment are preferable to actually removing healthy body parts. But in the end an adult can do what they want.