How do I rotating my 2D sprite and counter it back?

I have tried to make a rotation for my 2D sprite, I set it as prefab and spawn it using a code. This a sample of my rotating code, the 2D sprite already can rotate with that, but it keep rotating . how do I can stop it when it comes on 60 degrees and counter it back to 0 degrees then stop the rotating function? I put this code on update function and i use rigidbody2D on the prefab. For the result that i want is make some move like stick punching (pulling a stick up and then punch it down). Thanks

     Quaternion rot = transform.rotation;
     float z = rot.eulerAngles.z;
       
                         for ( t = 0f; t >= -40f; t -= 20)
                              {
             
                             z += t * Time.deltaTime;
                             rot = Quaternion.Euler(0, 0, z);
                             transform.rotation = rot;
 
                                }