how to properly scale gameobject in script

I'm trying to make a gun that the bullets growing in size while you hold down the fire key i got it working by just creating multiple instances of the object but i cant figure out how to destroy them after the next object is place. is there a better to scale it as to not run into this problem?

heres my code:

using System.Collections; using UnityEngine; using UnityEngine.UI;

public class gunfire : MonoBehaviour { public Rigidbody projectile; public Transform chargeSpawn; public GameObject bubble; private float chargeTime = 0; private float chargeRate = 2f;

 public Transform spawnpoint;
 public bool isGrowing = false;

 IEnumerator growCoroutine;
 void Start()
 {
     growCoroutine = growCor();
 }

 private void Update()
 {
     if (Input.GetMouseButtonDown(0))
         growStart();
     if (Input.GetMouseButtonUp(0))
         growStop();
 }
 IEnumerator growCor()
 {
     
     while (isGrowing) {
         Instantiate(bubble, spawnpoint.position, spawnpoint.rotation);
         bubble.transform.localScale += new Vector3(0.025f, 0.025f, 0.025f);
         var radius = transform.localScale.y;
         
         if (radius == 3.7) {
             growStop();
         }
         yield return null;

     }
 }


 void growStart() {
     if (!isGrowing) {
         isGrowing = true;
         StartCoroutine(growCoroutine);
     }
 }

 void growStop() {
     if (isGrowing)
     {
         StopCoroutine(growCoroutine);
         isGrowing = false;
         bubble.transform.localScale = new Vector3(1f, 1f, 1f);
         var radius = transform.localScale.y;
         float speed = (100 / radius);
         Rigidbody InstantiateProjectile = Instantiate(projectile, transform.position, transform.rotation) as Rigidbody;
         InstantiateProjectile.velocity = transform.TransformDirection(new Vector3(speed, 0, 0));
     }
 }

}