Time to get the parents actively involved. It is not ok, and he is likely allowed to do this at home as well. If he is "well behaved" at home, it is still time to get them involved.
Detail the behaviour you are seeing, and what you need to see change/ what your expectations are. Give a timeline for improvement, and if you do not see any, then he is not a good fit for your dayhome. Why put yourself through this day in and day out?
What is his behaviour at the centre? If time outs are not working, the consequence needs to change. Perhaps a loss of privleges?
Bottom line, Mom and Dad need to be helping or this is going to continue.