Best way is soap and water. If that doesn't help, try a mild solution of PBW at 0.25 to 0.5oz per gallon and let it sit for 20 - 30 minutes tops.
After cleaning with PBW, it's best to boil the rod a to re-seal and rehydrate the anodized layer. If you don't want to do PBW, you could also try boiling. It will break down some of the baked in goo and condition the rod at the same time.