Settings a rect transform to zero

Hi

I have a button that instantiates a textfield as a child of a panel in my canvas. But if I Instantiate it the anchor points are in the correct place, but the rect transform is completely off the road.. if I zero out all the rect transform properties while in play mode , the textfield looks just the way I want it.

Does anyone know how I can zero out the properties of a rect transform in code ?

this is what my Function looks like of the button :

public void TestButton(){

     GameObject go = Instantiate(prefabToInstantiate) as GameObject; 
     go.transform.SetParent(panelParent.transform); 


 }

Thank you