I know you can turn your single player world into a Minecraft Realm world but how do you do it the other way around?
Well as a young explorer, I thought about that, too.
Thankfully if you go into the .zip file in minecraft, you are able to find .realms. If you click it, you will find 3 folders and an additional .exe.
The 3 folders will be named whatever you put as a name. If you find the one you want, simply drag it to your existing saves in minecraft on files.