Is it permissible to expose the legs up to the knee and the arms up to the armpit in front of a non-mahram woman for the purpose of waxing?

If the woman is a Muslim, your 'awrah in front of her is what is between the navel and the knee, according to the majority of scholars. Thus, she is permitted to see your shins and arms. If she is a disbeliever, the prevalent view is that she is not permitted to see anything from you except the face and the palms of the hands. Therefore, it is not permissible to uncover the shins or arms for her.