UnityEditor.PrefabUtility.DisconnectPrefabInstance C# (CSharp) Method

        public static extern void DisconnectPrefabInstance(Object targetObject);
        /// <summary>

        public void ResetPreviewInstance()
        {
            if (m_PreviewUtility == null)
            {
                InitPreviewUtility();
            }

            DestroyPreviewInstance();
            if (palette != null)
            {
                m_PaletteInstance = previewUtility.InstantiatePrefabInScene(palette);

                // Prevent palette from overriding the prefab while it is active, unless user saves the palette
                PrefabUtility.DisconnectPrefabInstance(m_PaletteInstance);

                EditorUtility.InitInstantiatedPreviewRecursive(m_PaletteInstance);
                m_PaletteInstance.transform.position   = new Vector3(0, 0, 0);
                m_PaletteInstance.transform.rotation   = Quaternion.identity;
                m_PaletteInstance.transform.localScale = Vector3.one;

                string      assetPath    = AssetDatabase.GetAssetPath(palette);
                GridPalette paletteAsset = AssetDatabase.LoadAssetAtPath <GridPalette>(assetPath);
                if (paletteAsset != null)
                {
                    if (paletteAsset.cellSizing == GridPalette.CellSizing.Automatic)
                    {
                        Grid grid = m_PaletteInstance.GetComponent <Grid>();
                        if (grid != null)
                        {
                            grid.cellSize = GridPaletteUtility.CalculateAutoCellSize(grid, grid.cellSize);
                        }
                        else
                        {
                            Debug.LogWarning("Grid component not found from: " + assetPath);
                        }
                    }
                }
                else
                {
                    Debug.LogWarning("GridPalette subasset not found from: " + assetPath);
                }

                foreach (var renderer in m_PaletteInstance.GetComponentsInChildren <Renderer>())
                {
                    renderer.gameObject.layer          = Camera.PreviewCullingLayer;
                    renderer.allowOcclusionWhenDynamic = false;
                }

                foreach (var transform in m_PaletteInstance.GetComponentsInChildren <Transform>())
                {
                    transform.gameObject.hideFlags = HideFlags.HideAndDontSave;
                }

                PreviewRenderUtility.SetEnabledRecursive(m_PaletteInstance, false);

                clipboardView.ResetPreviewMesh();
            }
        }