[InitializeOnLoad]

[ExecuteInEditMode]

public partial class CSimulateEnv : MonoBehaviour

{

    static CSimulateEnv()

    {

       ClearLog();

    }

}

using System.Reflection;

using UnityEngine;

public class ClearTest : MonoBehaviour

{

    // Use this for initialization

    void Start()

    {

        ClearLog();

    }

    void OnGUI()

    {

        if (GUILayout.Button(" clear "))

        {

            ClearLog();

        }

    }

    public void ClearLog()

    {

        var assembly = Assembly.GetAssembly(typeof(UnityEditor.ActiveEditorTracker));

        var type = assembly.GetType("UnityEditorInternal.LogEntries");

        var method = type.GetMethod("Clear");

        method.Invoke(new object(), null);

    }

}