How To Get Rid Of Sun Tanned Skin?

Hello, I ve got one question: In the summer I got sunburn on my body on a beach & it s winter now, but those area is still little tanned comparing to those area where sun didn t touch me. It s almost 7 months. Of course it s not that dark, but still not my natural color. To be honest, I don t like it & want it to fade away. So my question is: Is it normal? Why does it need so much time to fade away completely? And can I faster process of fading it away or it s permanent now?