Thin films of glass-forming liquid crystalline molecules on float glass substrates showed restructuring-induced dewetting in the film thickness range of 40-100 Å upon increasing temperature after spin coating. This dewetting proceeded by the appearance of fluctuations at the free surface caused by restructuring taking place at the interface with the supporting substrate. Films thicker than 100 Å did not dewet despite significant modulations of the free surface. The amplitude of surface fluctuations with respect to the film thickness is shown to determine the film thickness range for dewetting.