F 30, new flat black mole on my leg, 1.5 mm diameter. Can it be an advanced stage melanoma? Derm said it is brown with black dots in center, to remove it

Start with biopsy. Any new skin lesion should be brought to the attention of your friendly dermatologist. The first step in skin cancer diagnosis is performed with a skin biopsy. If the dermatologist recommends a biopsy, I would have it taken off and allow for a pathologist to make the diagnosis.
Need it removed. There is no way to determine if this is melanoma or something benign without removing it and sending it to pathology for a diagnosis. If the dermatologist said to remove it then I would definitely suggest that you let them take it off and send it to pathology for analysis.