Uuummmmm ...... NEXT...... That child needs to be gone from your day care TODAY.... You are risking your children, the other children in your care , yourself and your business. Terminate today !!!! Have a letter ready at pickup saying what apples said or similar .... Such as
Dear parents
I regret to inform you that due to xxxx aggressive and often violent behaviour towards the other daycare children and myself that I will no longer be providing care effective immediately.
Regards crazy eight

You can add if you will be refunding any monies depending on what's in your contract with regards to immediate terminations. Speak directly to mom or dad or who ever picks up and tell them to their face and then say I have put it in writing for you for your records. Have all of his belongings at the door and say good bye