Is it harmful to change an eleven year old's surname against their wishes?

I don't think he should have too. My friend, lets say her name is Amanda Jones, Her step dad and parents chaned her name to "smith" but it got to confusing at school, so she changed it back to Amanda Jones. I really think the child should decide, its really not fair to bring in a step parent, and then making them change there last name, after going by it for 11 years. i find that stupid and mean.