Is it permissible for a young man who is studying and unemployed to take money from his family without their knowledge to cover his needs and personal expenses?

It is not permissible for a child to take from their parents' money without their consent, unless it is for essential sustenance and the parents withhold it from them. Taking money secretly is considered theft. The obligatory financial support for a child from their parents ceases upon the child reaching puberty and being able to earn a living. Educational expenses are not among the obligatory expenditures for parents after the child reaches puberty.