replacing default worlds

[franzanth]

Hi there. I recently tried to clear unused chunks from my worlds, mostly the end and nether. But every time I try to upload the modified worlds, they always end up creating new, separate worlds with the "ul_" prefix instead of replacing the default worlds.

So now I end up with:

world
world_nether
world_the_end
ul_world_nether
ul_world_the_end

Is it possible for me to completely delete the default nether and the end, and replace them with the files I've modified? I can't see a way to rename the "ul_" folders so I'm not sure what to do.

P.S. I've tried manually deleting those worlds, then reuploading my files, but they still end up having the prefix

Thanks!

[Punish]

[shnarglebluff]

HOW DO YOU CHANGE WORLDS