A simple tool for the Unity2D editor which allows you to hide sorting layers.

layer2d.cs

using UnityEditor;
using UnityEngine;

/*
 * This creative work (which includes code) is under exclusive copyright by default.
 * Unless specified otherwise by Tahar Meijs, nobody else may use, copy, distribute,
 * or modify this work without being at risk of take-downs, shake-downs, or litigation.
 * 
 * Testing code does not mean you will are allowed to keep on using this codebase for
 * your own personal / commercial gain. However, it is always encouraged to use this
 * code for educational purposes
 */

public class Layers2D : EditorWindow
{
	private SortingLayer[] m_sortingLayers = null;

	private Vector2 m_scrollPosition = Vector2.zero;

	[MenuItem("Window/Tahars Tools/2D Layers")]
	public static void ShowWindow()
	{
		GetWindow(typeof(Layers2D));
	}

	private void OnGUI()
	{
		m_scrollPosition = EditorGUILayout.BeginScrollView(m_scrollPosition);

		EditorGUILayout.BeginVertical();

		EditorGUILayout.BeginHorizontal();

		if (GUILayout.Button("Refresh Sorting Layers"))
		{
			RefreshLayers();
		}

		if (GUILayout.Button("Show All"))
		{
			ChangeSortingLayerVisibility("", true, true);
		}

		if (GUILayout.Button("Hide All"))
		{
			ChangeSortingLayerVisibility("", false, true);
		}

		EditorGUILayout.EndHorizontal();

		EditorGUILayout.EndVertical();

		EditorGUILayout.Space();

		ListAllSortingLayers();

		EditorGUILayout.EndScrollView();
	}

	private void ListAllSortingLayers()
	{
		if (null == m_sortingLayers)
			return;

		if (0 == m_sortingLayers.Length)
			return;

		EditorGUILayout.BeginHorizontal();

		EditorGUILayout.BeginVertical();

		foreach (SortingLayer sortingLayer in m_sortingLayers)
		{
			EditorGUILayout.BeginHorizontal();

			GUILayout.Label(sortingLayer.value.ToString());

			GUILayout.FlexibleSpace();

			GUILayout.Label(sortingLayer.name);

			GUILayout.FlexibleSpace();

			if (GUILayout.Button("Show"))
			{
				ChangeSortingLayerVisibility(sortingLayer.name, true);
			}

			if (GUILayout.Button("Hide"))
			{
				ChangeSortingLayerVisibility(sortingLayer.name, false);
			}

			EditorGUILayout.EndHorizontal();
		}

		EditorGUILayout.EndVertical();

		EditorGUILayout.EndHorizontal();
	}

	private void RefreshLayers()
	{
		m_sortingLayers = SortingLayer.layers;
	}

	private void ChangeSortingLayerVisibility(string layer, bool isVisible, bool applyToAll = false)
	{
		GameObject[] allSceneObjects = FindObjectsOfType<GameObject>();

		foreach(GameObject entity in allSceneObjects)
		{
			SpriteRenderer spriteRenderer = entity.GetComponent<SpriteRenderer>();

			// Has no sprite renderer component
			if (null == spriteRenderer)
				continue;

			if (applyToAll)
			{
				// Just apply the setting without looking at the layer name
				spriteRenderer.enabled = isVisible;
				continue;
			}

			if (layer == spriteRenderer.sortingLayerName && entity.activeInHierarchy)
				spriteRenderer.enabled = isVisible;
		}
	}

	private void OnDestroy()
	{
		// Window closes, so show every sprite again
		ChangeSortingLayerVisibility("", true, true);
	}
}