The possibility of the controlled removal of GaN nanowires (NWs) from an SiO_x inhibitor layer of patterned SiO_x/Si substrates has been demonstrated. It has been found that the wet KOH etching preserves the selectively grown GaN NWs on Si surface, whereas the GaN NWs grown on inhibitor SiO_x layer are removing. The effect is described by the difference in polarity between GaN NWs grown on a Si surface and NWs grown on a SiO_x inhibitor layer.