The good news is that there are many tips and tricks out there that can help brighten the tone of your skin
And bug fix
You can gradually change your skin tone from dark to light using skin lightening creams with hydroquinone vitamin C etc. However you would have to ask your dermatologist how to change it from black to white if you are looking for faster results. Expect to see a noticeable change in your skin tone if you decide to use skin bleaching creams in roughly 6 months with proper use of sunscreen. With the summer coming up, going in the sun will reverse any skin lightening you are trying to do if you have already dark skin