You should be able to edit ones you create via the brand directory, until they have been reviewed by a brand admin they will show only the basic information entered in the brand directory. The rest will say "Hidden until reviewed".
You can provide details of what needs to be changed for a given brand in the #brand-directory-issues channel on the discord server of any brand entries that need to be altered or fixed. A brand admin will see those comments and review/update the brand.
NOTE: Brand admins like all who support Wardrobe do this on a volunteer basis. If your pointing out an issue with a brand that requires updates or there are duplicates that need to be merged. They require the relevant information. For example if the landmark has changed, please provide the new landmark.