Try Destroy(gameObject);

I don't believe there's a parameteless overload for the Destroy method.

I did't want to copy the hole text but i tried

Destroy(planetLabels[i]);

and

Destroy(planetLabels[i].GetComponent(GameObject));

because the component of the object is GUIElement

@simeonradivoev

You wouldnt call its gameobject component like that, try this

Destroy(planetLabels[i].gameObject);

You may need to edit the length of your array to remove the empty slot. If you are using Array() you can use remove at

planetLabels.RemoveAt(i);

which will be called after you call destroy, if you remove the slot first you wont have the path to that gui text

I Instantiated a GameObject not a GUIText, and then Destroy worked as hoped. Also a can get/set the information for the GUIText from the object I just used for example NameOfGUIText.guiText.text = "some text"

@simeonradivoev

If you did want to reference the GUIText itself you can use the method i provided( adding .gameObject to the array ref). Sounds like you found your answer?