This minizes the Unity window (Editor or Build) from code. Only tested on windows.

Minimize.cs

using UnityEngine;
using System.Runtime.InteropServices;

public class Minimize : MonoBehaviour {
    private void OnMimize() {
        ShowWindow(GetActiveWindow(), 2);
    }

    [DllImport("user32.dll")]
    private static extern bool ShowWindow(IntPtr hwnd, int nCmdShow);
    [DllImport("user32.dll")]
    private static extern IntPtr GetActiveWindow();
}