I'm no expert, but I don't think that there's a way to edit the official worlds, including store worlds in create a world, unless you want to recreate the world from scratch just to change that minor issue you have with the roads. You're better off just creating a new world with a similar theme if you want to do that. If you want to just use those roads in a new world, I recommend that you just replace the sidewalks with another texture. You might be able to find one on this thread. In case you forgot about it, Auntielynds provided us with a bunch of links to different textures there that you could use. You will have to scroll down a bit through to get to them. You should be able to find something useful there.
CAW FAQ'S........LINKS TO TUTORIALS, AND RESOURCES. TEXTURES, & TROUBLESHOOTING
https://forums.thesims.com/en_US/discussion/278761/caw-faqs-links-to-tutorials-and-resources-textures-amp-troubleshooting/p1
