I am 28 years old male. My weight is 115kg. My brest size is fairly large than a normal male brest. How I can reduce my brest size?

Gynecomastia. Gynecomastia (benign enlargement of breast tissue in a male) is commonly related to an subtle hormonal inbalance. It is very common in pubertal males and very old. It can also be a medication side effect or related to underlying liver disease. Most often a cause can't be identified. Surgical excision is usually considered cosmetic & best performed by plastics w/liposuction to avoid deformity.
Breast Size. Loosing weight can help, but ultimately surgery may be the best option for you.