There is no spiritual or legal reason if you desire to change your name, that you can't. Many of the names were changed of those who become disciples of Jesus.
God Changed Jacob's name to Israel, Abrahms name was changed to Abraham, Saul (NT) to Paul and there are others as well. Nothing wrong with name changes. Bless you brother.
Father I pray for my young brother, Lord be of comfort to him and ease his pain, let him know that he has done nothing wrong and give him a mind of forgiveness and the knowledge that he is created in your IMAGE and that all things are possible. And that his name is REDEEMED