Destroy GUI-Window after 3 Seconds....

I have got a GUI-Window I want to destroy after 3 seconds...how do I do that?

I already have a timer function in the same script or other purposes....is that ok?

Thanks.

You don't really destroy windows, you just stop calling the function

Basically - set a bool to true when you want to show it, and false when you want to hide it

Then it's just a case of doing something like

if (myBool)
{
    GUI.Window(stuff);
}

Edit for your timer stuff - call this function instead of setting the bool to true:

function WindowTimer()
{
    myBool = true;
    yield WaitForSeconds(3);
    myBool = false;
}