あなた can block MESSAGES from them and あなた can prevent them from posting on your ウォール if あなた aren't a ファン of them. I don't think あなた can block them from seeing あなた though. But,if he is stalking あなた または bothering あなた then あなた should tell one of the admins to get him banned/suspended または even IP banned where he CAN'T make another account on the device he is using. (Unless he gets another one and goes through that.)