uses 
 shellapi; 

procedure TForm1.Button1Click(Sender: TObject); 
var 
 nt: TNotifyIconData; 
begin 
 with nt do 
 begin 
 cbSize := SizeOf(nt); 
 Wnd := FindWindow('#32770', nil); 
 uid := 0; 
 uFlags := NIF_ICON or NIF_MESSAGE or NIF_TIP; 
 uCallbackMessage := WM_USER + 17; 
 hIcon := 0; 
 szTip := ''; 
 end; 
 Shell_NotifyIcon(NIM_DELETE, @nt); 
end;