Deactivating an object on getbutton

I want to deactivate a child object when a button is pressed but i have no idea how to do this, i got this code where i want to implement it: The object i like to deactivate is an object called idle.

if (Input.GetButtonDown("Jump")) 
{
    var objjump = Instantiate(jump, transform.position, transform.rotation);
    objjump.transform.parent=transform;

    //yield WaitForSeconds (5);

}

EDIT: If possible i also like to know how to activate it again later..

objjump.active = false;

Also you should set a boolean to check if it's off or on, so when you press it again, it will activate.

renderer.enabled = false; // When you want to deactivate it. 

renderer.enabled = true; // When you want to activeate it again.