You can dremel the spot you describe but that may not be your actual rub point. Aggressive wheels / tires rub at the metal fender around 4 or 5 o'clock if you are facing the passenger side of the car. You can also add negative camber to help the situation. There is no easy fix for metal the fender rub.
'08 E90 M3 - Alpine White - Sold
'13 E92 M3 - Silverstone II - Sold
'04 E46 M3 - Jet Black - BBS E88, KW Clubsports, Brembo BBK, SuperSprint Exhaust