How to hard reset htc pg58130 ?

iPhone 4. 16gb. Unlocked. 1 year old
Unlocked black iPhone 4. Bought from apple store June last year. Just upgraded to the Samsung galaxy sIII. Looking fast sale so no offers on £150 as that is a very good price. Phone is in brilliant condition and was very well looked after, always had a cover on it so there is no scrapes or anything. Will meet anyone who wants to inspect it before buying but I guarantee the first to see will buy. It is a definite bargain for the price. May listen to offers for a swap but only if you are serious. Will travel to meet if needs be. B Phone me (Jodie) on 07411801806 Still have phone. No timewasters please.