pocketmine\Server::removeOnlinePlayer PHP Method

    public function removeOnlinePlayer(Player $player)
    {
        if (isset($this->playerList[$player->getRawUniqueId()])) {
            unset($this->playerList[$player->getRawUniqueId()]);
            $pk = new PlayerListPacket();
            $pk->type = PlayerListPacket::TYPE_REMOVE;
            $pk->entries[] = [$player->getUniqueId()];
            Server::broadcastPacket($this->playerList, $pk);
        }
    }