This? I believe I found it ages ago by Yashied Rover, though didn't save the URL link.   #include <APIConstants.au3>
#include <GUIConstantsEx.au3>
#include <WinAPIEx.au3> ; www.autoitscript.com/forum/topic/98712-winapiex-udf/
Example()
Func Example()
	Local $hGUI = _GUICreate_NoIcon("_GUICreate_NoIcon()")
	GUICtrlCreateLabel("Example Label", 10, 10, 150, 25)
	GUISetState(@SW_SHOW, $hGUI)
	While 1
		If GUIGetMsg() = $GUI_EVENT_CLOSE Then
			ExitLoop
		EndIf
	WEnd
	GUIDelete($hGUI)
EndFunc   ;==>Example
Func _GUICreate_NoIcon($sTitle = "", $iWidth = -1, $iHeight = -1, $iXpos = -1, $iYpos = -1)
	Local $hGUI = GUICreate($sTitle, $iWidth, $iHeight, $iXpos, $iYpos, BitOR($WS_CAPTION, $WS_SYSMENU), $WS_EX_DLGMODALFRAME)
	Local $hIcon = _WinAPI_GetClassLongEx($hGUI, $GCL_HICON)
	_WinAPI_DestroyIcon($hIcon)
	_WinAPI_SetClassLongEx($hGUI, $GCL_HICON, 0)
	_WinAPI_SetClassLongEx($hGUI, $GCL_HICONSM, 0)
	Return $hGUI
EndFunc   ;==>_GUICreate_NoIcon