How can i get rid of the skin on my bikini that look just like acanthosis ? i am very very pale white (first shade makeup foundation)

Several ways: First you should see a dermatologist to confirm it really is acanthosis nigricans. Then, you want to figure out what may be contributing, as it appears often treating a contributing condition can help lighten it's appearance - whether it be weight, diabetes, thyroid related. Otherwise topical retinoids, dermabrasion and laser therapies are also possible treatment options. Hope this helps.