Skin types / tones

Can you remove tattoos on different skin tones? Can you remove black ink on darker skin tones?Can you treat a tattoo that's done over a scar? I have a birthmark under my tattoo, can you still treat it?Can you treat tattoos over stretch marks? I have moles under or near my tattoo, can I still have treatment? What area of the body can you not treat?Can you remove tattoos on sensitive areas?I have Vitiligo, can you treat me?Can you remove coloured ink on darker skin tones?