When I was about the same age, I was teased horribly by other children in my class. I was also a swimmer so it didnt help.
While my mom always encouraged me to be confident and proud, but it didnt stop the fact that the teasing was affecting me.
My mom allowed me to shave my legs. I can remember the huge relief and not feeling so self conscious.
If it is because she is being teased, and it were my daughter, I would let her, but perhpas waxing is a better option as it keeps the hair away longer.