You have to manually do it by editing the xml file gamelist.xml within the rom folder. I would suggest scraping manually next time. It takes forever, but at least you know everything will be correct and you only have to do it once.
I haven’t played around a ton with the builtin scraper but if I remember correctly there is an option to only scraper things missing images. You might be able to just delete everything in your gamelist.xml and images that is incorrect then manually scrape to get the real data. But the amount of time required inspect everything for issues might be comparable to manually scraping everything.