I heard that "the later you hit the puberty,the more taller you will become as an adult".if this is the case,than how can we delay puberty?

You can't: You can to some extent avert "precocious" puberty (that is unnaturally early) by insuring proper nutrition. But it is largely genetic.

Let it run cours: No good way to affect the natural process. Girls not exposed to higher estrogens in diet, vegetarians, do, however seem to enter puberty late.

Misguided idea: While it is true some kids who enter puberty later will be taller, it is because their genetic makeup follows that blueprint.You become as tall as your genes dictate, not because puberty takes longer. Delaying puberty in people destine to be shorter would just make them shorter for a longer period before growth stopped.