function OnGUI() {
    if (GUILayout.Button ("Disconnect first player")) {
        if (Network.connections.Length > 0) {
            Debug.Log("Disconnecting: "+
                Network.connections[0].ipAddress+":"+Network.connections[0].port);
            Network.CloseConnection(Network.connections[0], true);
        } 
    }    
}

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
    void OnGUI() {
        if (GUILayout.Button("Disconnect first player"))
            if (Network.connections.Length > 0) {
                Debug.Log("Disconnecting: " + Network.connections[0].ipAddress + ":" + Network.connections[0].port);
                Network.CloseConnection(Network.connections[0], true);
            }
        
    }
}

import UnityEngine
import System.Collections

class example(MonoBehaviour):

    def OnGUI():
        if GUILayout.Button('Disconnect first player'):
            if Network.connections.Length > 0:
                Debug.Log(((('Disconnecting: ' + Network.connections[0].ipAddress) + ':') + Network.connections[0].port))
                Network.CloseConnection(Network.connections[0], true)