Renaming a world/resetting nether

[awesomeonenick]

Hi, in preparing for the 1.16 update I want to be able to reset my nether, but keep the spawn area.

To do this I need to download the world and delete all the region files that I do not need, and re-upload it and delete the original nether world. The problem with this is that when re-uploaded, the file is renamed to "ul_world_nether" instead of "world_nether". This causes "world" to just regenerate the "world_nether" file rather than using the one I've uploaded. As a solution I am trying to download all 3 world files and re-upload all of them so they are compatible with each other (ul), and so that I can reset the nether how I want later on. The issue with this is that my 3gb overworld is not successfully uploading to file.io, and so I am not sure what to do. 

If there is any way to rename a world on my server, please let me know, and if there isn't one, minehut please make a way.

[nullific]

try installing the plugin Multiverse, it may have a command for renaming worlds.