I'd recommend a burn. You can use a Harbor Freight weed burner to burn your drum if you are in a residential area. No need to fill it with wood. The weed burner burns plenty hot and will burn off any residue left.
Just be aware that you can warp your drum if the flame is left in one spot too long. Also, try not to look directly into the drum while using the weed burner or you will discover the "burnt off my arm hair and eyebrows mod" from the backdraft of heat.