How to destroy the World?

Persuade the entire population of China to all jump off a chair at the same time (Obviously one chair each, not just one huge chair...) which should be enough to take the Earth out of it's orbit and on a course which will cause it to spiral into the Sun and be destroyed (or possibly collide with Venus or Mercury on the way in). How you actually go about doing this is up to you, but I'd suggest learning Mandarin as a first step, followed by extensive cosmetic surgery. You'll then need to seize the central transmitting station of the Chinese Communist Party, although you may wish to wait until after the stitches from your surgery have come out.