How can gynaecostia be treated?

Gynecomastia? Do you mean gynecomastia? Enlarged male breasts? It depend on the size of the breasts. If there is just excess fat but not too much extra skin, liposuction works well. But if there is a lot of extra skin, that needs to be removed surgically.
Surgery. The best treatment is surgery, which usually involves liposuction and gland excision.
Liposuction. You should consult a qulaified plastic surgeon or asthetician to discuss your options.