Do I need to cancel my family's resident permits (which expires in 3 months' time) before leaving?

Hello, I have a residence permit and valid Z type till end of June 2016. Based on these I got dependent resident permit and entry permit for my wife and daughter. Now, my contract with my contract ends 31st March (3 months before expiry of my Z type) and they request my passport and my family's for visa cancellation process. My company pays for my charges but I have to pay for my family's and the air tickets. These I consider rather too expensive and I'm wonder if I really have to cancel for my wife and daughter and go through the expense. So I want to know: Is it not appropriate to leave 1st week in April without going for my family's cancellation? Since their entry permits and residence permits expires by June anyways and we don't have any plans to return to PRC right now, do they need to go for the cancellation process? What could be the potential offence if they just leave with me early in April? Please I look forward to your prompt advise