I need help with my 4yr old student?

i am a preshool teacher. i have a staff child in my cl and the boy is the type of child that has no respect for athorety. he slapped me in the face becuase i told him not to throw toys. his mom my coworker in the ajoining cl doesn't seem to think his behavior is a problem.i've had it and i don't kow what to do. he cannot be moved from the clroom and i need help.