How do you remove cookie burn marks on a brand new baking sheet?

To remove cookie burn marks from a new baking sheet, first soak the sheet in warm soapy water for about 15-30 minutes. After soaking, use a non-abrasive sponge or cloth to gently scrub the affected areas. If stains persist, a paste of baking soda and water can be applied to the marks, left for a few minutes, and then scrubbed off. Rinse thoroughly and dry the baking sheet before using it again.