Transform.localRotation

Description

The rotation of the transform relative to the parent transform's rotation.

Unity stores rotations as Quaternions internally. To rotate an object, use Transform.Rotate. Use Transform.localEulerAngles for modifying the rotation as euler angles.

using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour {
    void Example() {
        transform.localRotation = Quaternion.identity;
    }
}