drill your bottom intake holes and build as big of a fire in the drum with any scrap wood as you can and let it burn until the outside is black and all of the paint has peeled off, or if you have a weed burner that hooks up to a propane tank, lots of people use them to burn off the paint and liners.
Robert aka Big Bob. :typing:
Home built 120 gallon stick burner on wheels,
Master Built 7-in-1 vertical,
Master Forge Charcoal grill,