How Do You Block On iMessage Or FaceTime?

hello my name is seth , i was wandering how to block this kid on imessage and facetime . he keeps on imessagng me and facetiming me . when he texts me and i dont answere back he spams spams spams he does letter by letter then does one sentece with ? or ! . andwhen u facetimes me and i dont answere he calls the co*ps on me . i accendeantly swor , because i was mad and when im mad im not me so when im not me i act like a bad kid and i dont even know what im doing when im not me . so he'll call the cops on me if i dont answere . please how do you block ?