how to destroy empty object of children i generated after some move

Questions & Answers
1

how to destroy child object after some position reach?
i make empty object (and instantiate some prefab) from the position of other empty object and then give the empty obejct force to move.
i want to destroy this moved empty object (and their child prefab) after some postion reach, just like some bullet being shoot i need to destroy it or else there will be soo many empty object lying around

here my code

void Update()
    {
        if (Input.GetKeyUp("space")==true)
        {
            spawn();
        }


        if (GetComponentInChildren<Transform>().position.z == 3)
        {
            Debug.Log("ye");
        }

void spawn()
    {
        GameObject tempempty = new GameObject("basis");
        tempempty.AddComponent<Rigidbody>();
        tempempty.GetComponent<Rigidbody>().useGravity = false;
        tempempty.transform.SetParent(this.transform);
        for (int x = 0; x < luas.x; x++)
        {
            GameObject tempbasisy = Instantiate(basis);
            tempbasisy.transform.SetParent(tempempty.transform);
            tempbasisy.transform.position = new Vector3(x, 0, 0);

        }
        tempempty.GetComponent<Rigidbody>().AddForce(0, 0, 100);

    }

im sorry i ask this basic question, im new to coding and unity

2

Destroy(tempbasisy); If you destroy the parent all children are also destroyed. Altho, if you are doing it a lot you might want to use pooling instead…
Sorry, if you need to know when to destroy it:

Vector3 origin;
float destroyDistance;
origin=tempbasisy.transform.position;
if(Distance(tempbasisy.transform.position,origin)>destroyDistance)
Destroy(tempbasisy);