I dont think GuiText has a renderer, what you could do is access the GuiText component or just disable the whole gameobject. So for the gameobject:
var g1: GUIText;
function Start(){
g1.text = "3";
yield WaitForSeconds(1);
g1.gameobject.active = false;
}
And for the component:
var g1 : GUIText;
function Start(){
var guiComp1 = g1.GetComponent(GUIText);
//bla bla code jubberish like I did in the previous code slot
yield WaitForSeconds(1);
guiComp1.enabled = false;
}
at least 1 of them would work! Good luck with your project!