Making a Trail Used for Detection Invisible

Hi all,

I know this has probably been answered before, but I am having a hard time finding a solution. I am not an experienced programmer and am working off code written by someone I had hired to finish this project (and is now no longer responding to messages).

There is code written into this program (pasted below) which renders a trail behind the player object. This trail is used by another object in the game to detect when the player has made a circle around an object. It is currently set to a default material which does not appear to be editable. I tried adding a material to the object to change the color and while that seems to work, I cannot find a way to make it invisible.

Code (CSharp):

1. using UnityEngine;
2. using System.Collections;
3.  
4. public class DrawALine : MonoBehaviour {
5.     public GameObject Dot;
6.     public GameObject Cube;
7.     public float Distance = 0.0F;
8.     Vector3 PreviousPos;
9.  
10.     // Use this for initialization
11.     void Start () {
12.         Cube = GameObject.FindGameObjectWithTag("Player");
13.         Instantiate(Dot, transform.position, transform.rotation);
14.         PreviousPos = Cube.transform.position;
15.     }
16.     // Update is called once per frame
17.     void Update () {
18.         //Distance = Vector3.Distance(PreviousPos, Cube.transform.position);
19.         Cube = GameObject.FindGameObjectWithTag("Player");
20.         Distance = Vector3.Distance(PreviousPos, Cube.transform.position);
21.         if (Distance > .1) {
22.      //       Debug.Log("You took a Step");
23.             Instantiate(Dot, Cube.transform.position, Cube.transform.rotation);
24.             PreviousPos = Cube.transform.position;
25.         }
26.         //Instantiate(Dot, Cube.transform.position, Cube.transform.rotation);
27.     }
28. }
29.  

Please let me know if additional photos or code would be helpful, thank you!