Purchase paint strippers that come in gel form. Make sure that the strippers are non-caustic, compatible with aluminum and, specifically, paint strippers. Apply the paint stripper to the paint brushes and sweep the brush over the affected area. Aircraft Paint Stripper works very well.
Purchase Peel Away 6 or Peel Away 7 and apply the paste to the affected areas if the paint strippers did not complete the job. Cover the area with a cloth in order for the paste to absorb more thoroughly.
Purchase a Mr. Clean Magic Eraser. Soak the pad in water and scrub the affected area.
Spray Permatex Gasket remover on the affected area.
Visit a service center that has a Soda Blasting or Bead Blasting machine to remove any left over paint from aluminum.