Send it into Sol. THAT'S the only way to be sure. If you nuked it, even if you saturation bombed every square inch of the surface, then life would persist on the sea bottom and deep underground and eventually evolve out again. And spinning the globe faster suddenly would not increase gravity. It might possibly make everything on the surface fly off into space, but probably not. Most of the stuff described here would only be good at eradicating humans or terrestrial organsims.