OnDestroy is called to close the EditorWindow window.
A simple example of OnDestroy()
// Close the window when the Button is pressed. The window // will receive an OnDestroy() call. using UnityEditor; using UnityEngine; using UnityEngine.UIElements; public class OnDestroyExample : EditorWindow { [MenuItem("Examples/OnDestroy Example")] public static void ShowExample() { OnDestroyExample wnd = GetWindow<OnDestroyExample>(); wnd.titleContent = new GUIContent("OnDestroy Example"); } public void CreateGUI() { Button closebutton = new Button(); closebutton.text = "Close!"; closebutton.clicked += () => { this.Close(); }; rootVisualElement.Add(closebutton); } void OnDestroy() { Debug.Log("Destroyed..."); } }