Depends on the aircraft. Concorde, for instance used electrical deicing system on its engine inlets, air data probes and wing leading edges to prevent ice accumulation during subsonic climb and descent.
Supersonic cruise typically takes place in the upper stratosphere and beyond, where no weather save only a few very powerful thunderstorms ever penetrates. Secondly, deicing equipment would not be needed there as supersonic cruise typically causes a great deal of airframe heating due to atmospheric friction. A Concorde cruising at Mach 2 typically had skin temperatures in excess of 150° F over its surface and the SR-71 encountered skin temperatures from several hundred to 1200° F over its airframe. High supersonic and hypersonic aircraft would be even worse. Airframe icing will not form under these conditions.
Information on deicing systems on supersonic business jets (SSBJs) remains largely proprietary at this point, but I suspect they use similar schemes to that of the Concorde. IF, that is, one of these designs finally goes on test flights (Ahem, Boom!) and stops with the CGI eye candy.