Yes, a Jain person can choose to adopt another religion, because Jainism does not force belief by coercion.

But from the Jain point of view, leaving Jain dharma means leaving the path of Ahimsa, Satya, Asteya, Brahmacharya, and Aparigraha as practiced in Jain life. A person should make such a decision very carefully, with respect for parents, tradition, and their own inner conscience.

If someone has taken vratas or special Jain vows, they should reflect seriously before changing their path, because vows carry spiritual responsibility.

In simple terms: legally and personally, yes; spiritually, it is a serious decision in Jain dharma.