How to Remove Pit Marks in my 68 Tail Panel

That is anodized aluminum. If they aren't too deep you can strip the anodizing and sand them out. Finish by polishing the raw aluminum or send it off to be re coated.
Should I just sand with 100 grit until the pot marks are out? or should I sand with 100, then 200, then 400 etc, until the marks are out?