Registration. Child born in the UK. Oath and pledge
If you are a child born in the UK, and at the time of your birth none of your parents were British citizens or settled in the UK, but you have been registered as a British citizen because, while you were a minor, any of your parents became British or settled or a member of the UK armed forces, or because you have lived in the UK for the first 10 years of your life, then there is no legal requirement for you to attend a ceremony and take the oath and pledge.
Only adults naturalising as British citizens must attend a ceremony and take the oath of allegiance and the pledge. You may do so if you are still a minor at the date of the ceremony, if you want to. If you do not attend the ceremony, you can collect your certificate of registration from the local authority. You or your parents must speak with them and make the arrangements.
If you apply to be registered as a British citizen while you are a minor, but you become an adult by the time the case is decided, you will have to attend the ceremony and take the oath and pledge.
If you want to apply for British citizenship or for a British passport and need specialist advice, feel free to contact me. Please note that I am an accredited immigration adviser, not an employee of the UK Visas and Immigration. I charge fees for the advice provided.