Disabling a gui texture through triggers

The following script allows me to enter a trigger, and will display a gui texture. but i also want the gui texture to dissapear when i exit the trigger. how would i do this? i tried destroying but it destroyed the prefab also… can i somehow disable it?
script:

function OnTriggerEnter (PlayerCollider : Collider)
{
if(PlayerCollider.gameObject.name == “player”)
{

	var instance : GUITexture = Instantiate(openDoorText,Vector3(.5, .5, 0), Quaternion.identity);
	
	
	}

}

You must have been trying to destroy the prefab and not the instance, therefor you should place a variable outside of the scope of the OnTriggerEnter function so you can access it on other functions and in your case OnTriggerExit:

var guiTexturePrefab : GUITexture;

var doorUp : AnimationClip; 
var timer : float = 6.0;
private var instance: GUITexture;

function OnTriggerStay (mytrigger : Collider) 
{
	if(mytrigger.gameObject.name == "player" ) 
	{
		door = gameObject.Find("door");

		if(Input.GetButton("openDoor"))
			door.animation.Play("hoistDoorUp");
	}
}

function OnTriggerEnter (PlayerCollider : Collider) 
{ 
   if(PlayerCollider.gameObject.name == "player") 
      instance= Instantiate(guiTexturePrefab,Vector3(.5, .5, 0), Quaternion.identity);
}
function OnTriggerExit (PlayerCollider : Collider) 
{ 
   if(PlayerCollider.gameObject.name == "player" && instance) 
      Destroy(instance);
}

var doorUp : AnimationClip;
var instance : GUITexture;
var timer : float = 6.0;

function OnTriggerStay (mytrigger : Collider) {

if(mytrigger.gameObject.name == “player” )
{

door = gameObject.Find("door");

if(Input.GetButton(“openDoor”))

	door.animation.Play("hoistDoorUp");
}

}

function OnTriggerEnter (PlayerCollider : Collider)
{
if(PlayerCollider.gameObject.name == “player”)
{

	 instance = Instantiate(instance,Vector3(.5, .5, 0), Quaternion.identity);
	
	
	}

}

function OnTriggerExit (playerCollider : Collider)
{
if(playerCollider.gameObject.name == “player” && instance)

	Destroy(instance);

}