replace scan with better one?

i uploaded a pdf but realized afterward that it has sub-par resolution. i fixed the problem and made a new scan, is there any way i can replace the old scan with the new one?

delete file?

I was wondering if you could help me... I uploaded a zine to this site "984 Miles Until Happiness". I just noticed the pages are out of order. How do I delete it and reload the new one with the updated correct page sequence? When I uploaded the file I wasn't a member. But I am now... Thank you!