What is the ruling on my remaining in a college that I entered through cheating, by having my sister take the aptitude test on my behalf?

The sister's action of entering the exam in place of her sister is a forbidden act of cheating and deception, from which one must repent. The sister concerned must inform the college of the truth of the matter and let them decide. If the required drawing is of inanimate objects, there is no harm in it. However, if it is of living beings, then it is forbidden, and it is not permissible to study in this field. There is no obedience to parents in disobedience to Allah.