error CS0246

Hello! An error appears on the build. The error string - using UnityEditor;

Here's the script:

 using UnityEngine;
 using System.Collections;
 using UnityEditor;
 
 
 [CustomEditor (typeof(VehicleSelect))][CanEditMultipleObjects]
 public class VehicleSelectEditor : Editor
 {
     public override void OnInspectorGUI ()
     {
 
         serializedObject.Update ();
 
         EditorGUILayout.Space ();
 
         GUI.color = Color.green;
         EditorGUILayout.Space ();
         EditorGUILayout.HelpBox ("\n                           Vehicle Select System\n", MessageType.None);
         EditorGUILayout.Space ();
         GUI.color = Color.white;
 
 
 
 
 
 
         EditorGUILayout.HelpBox ("List of the cars", MessageType.None);
 
         EditorGUILayout.PropertyField (serializedObject.FindProperty ("vehicles"),
             new GUIContent ("Vehicles", "Drag youre car prefabs"), true);
 
         EditorGUILayout.Space ();
 
         EditorGUILayout.HelpBox ("Vehicle spawn point", MessageType.None);
         EditorGUILayout.PropertyField (serializedObject.FindProperty ("point"),
             new GUIContent ("Spawn Point", "Drag spawn point transform"), true);
         EditorGUILayout.Space ();
 
 
 
         EditorGUILayout.HelpBox ("List of the car prices", MessageType.None);
         EditorGUILayout.PropertyField (serializedObject.FindProperty ("Lock"),
             new GUIContent ("Lock Icon", ""), true);
         EditorGUILayout.Space ();
         EditorGUILayout.PropertyField (serializedObject.FindProperty ("LevelNumText"),
             new GUIContent ("Level Unlock Text", ""), true);
         EditorGUILayout.Space ();
         EditorGUILayout.PropertyField (serializedObject.FindProperty ("carsLevels"),
             new GUIContent ("Ech Car LevelUP Need", ""), true);
         EditorGUILayout.Space ();
 
 
         EditorGUILayout.HelpBox ("Icon - Button - Shop", MessageType.None);
         EditorGUILayout.PropertyField (serializedObject.FindProperty ("Lock"),
             new GUIContent ("Lock Icon", "Drag lock icon image   "), true);
         EditorGUILayout.PropertyField (serializedObject.FindProperty ("Shop"),
             new GUIContent ("Shop Window", "Drag Shop Window image   "), true);
 
         EditorGUILayout.PropertyField (serializedObject.FindProperty ("Buy"),
             new GUIContent ("Buy Button", "Buy Button Object   "), true);
         EditorGUILayout.Space ();
 
         EditorGUILayout.PropertyField (serializedObject.FindProperty ("vehiclePriceText"),
             new GUIContent ("Vehicle Price Text", "Drag Vehicle Price Text   "), true);
         EditorGUILayout.Space ();
 
 
 
         EditorGUILayout.HelpBox ("Main Level Name", MessageType.None);
         EditorGUILayout.PropertyField (serializedObject.FindProperty ("levelName"),
             new GUIContent ("Level Name ", "Enter Main Scene Day Mode Name  "), true);
         EditorGUILayout.Space ();
 
         EditorGUILayout.HelpBox ("Loading Window", MessageType.None);
         EditorGUILayout.PropertyField (serializedObject.FindProperty ("Loading"),
             new GUIContent ("Loading Object", "Drag Loading GameObject  "), true);
         EditorGUILayout.Space ();
 
         EditorGUILayout.HelpBox ("Customization", MessageType.None);
 
         EditorGUILayout.PropertyField (serializedObject.FindProperty ("mainMenu"),
             new GUIContent ("Main Menu", "Drag RingSport Component  "), true);
         EditorGUILayout.PropertyField (serializedObject.FindProperty ("customizeMenu"),
             new GUIContent ("Customize Menu", "Drag RingSport Component  "), true);
         EditorGUILayout.PropertyField (serializedObject.FindProperty ("selectButtons"),
             new GUIContent ("Select Buttons", "Drag RingSport Component  "), true);
 
         serializedObject.ApplyModifiedProperties ();
 
     }
 
 }