I've purchased aluminum prints from two other sources. One recommends --
". . . a microfiber towel for the best results along with Isopropyl alcohol or Meguiar’s Cleaner Wax."
The other says --
". . . can be cleaned easily with any commercial glass cleaner."
I can't speak to any of those methods as, so far, a slightly damp microfiber cloth (distilled water) has done the trick. Proceed with caution!