code: public function chatDelUser($chat, $peer)
      {
          $chat = $this->escapePeer($chat); //Not escapeStringArgument as chat needs underscores if spaces in name
          $peer = $this->escapePeer($peer);
  
          return $this->exec('chat_del_user ' . $chat . ' ' . $peer);
      }
docs: Deletes $peer from $chat
  
  @param        $chat
  @param string $peer
  @return mixed