array question

so i need to remove an element of an array NO LIST!!!

so, i tried use removeAt but it gives me an error and doesn't remove the element: missing method expectation

here's the code:

 var waypoints : GameObject[];
 var closestWaypoint : GameObject;
 @HideInInspector
 var distance = Mathf.Infinity;
 var moveTowardWaypoints : boolean;
 var speed : float;
 var maxSpeed : float = 2;
 
 var horizontalMovement : Vector2;
 var lastWaypoint : GameObject;
 var lookForNewWaypoint : boolean;
 
 function Update()
 {
     transform.LookAt(closestWaypoint.transform);
     transform.rotation.x = 0;
     transform.rotation.z = 0;
     
     horizontalMovement = Vector2(rigidbody.velocity.x, rigidbody.velocity.z);
     if (horizontalMovement.magnitude > maxSpeed)
     {
         horizontalMovement = horizontalMovement.normalized;
         horizontalMovement *= maxSpeed;
     }
     
     rigidbody.velocity.x = horizontalMovement.x;
     rigidbody.velocity.z = horizontalMovement.y;
     
     waypoints = GameObject.FindGameObjectsWithTag("Waypoint");
 }
 
 
 function LateUpdate()
 {
     if (lookForNewWaypoint)
     {
         for (var go : GameObject in waypoints)
         {
             var diff = (go.transform.position - transform.position);
             var curDistance = diff.sqrMagnitude;
             if (curDistance < distance)
             {
                 closestWaypoint = go;
                 distance = curDistance;
                 lookForNewWaypoint = false;
             }
         }
     }
     
     
     if (lastWaypoint)
     for(var i : int = 0; i < waypoints.Length; i++)
     {
         if(waypoints[i].gameObject == lastWaypoint)
         {
             waypoints.RemoveAt(i);
         }    
     }
 }
 
 
 function FixedUpdate()
 {
     rigidbody.AddRelativeForce(0,0,1 * speed);
 }
 
 
 function OnTriggerEnter(col : Collider)
 {
     if (col.transform == closestWaypoint.transform)
     {
         if (!lastWaypoint)
         {
             lastWaypoint = col.gameObject;
             lookForNewWaypoint = true;
         }
     }
 }