for(int i = 0; i < myArray.Length; i++){
    spriteRenderer = myArray[i].GetComponent<SpriteRenderer>(); //inefficient

    if(spriteRenderer.color.a == 0){
       // delete gameobject from world
       // to do
    } else {
     spriteRenderer.color.a = Mathf.Lerp(spriteRenderer.color.a,0,Time.deltaTime * fadeSpeed);
    }
}

public class MyCustomObject : MonoBehaviour {
	public SpriteRenderer spriteRenderer;
	public SomeOtherComponent someOtherComponent;

	public void FadeOut () {
		spriteRenderer.color = ...
	}
}

...

MyCustomObject[] myCustomObjects = new MyCustomObject[100];

...