Question: Is it possible to undo a "move edit"?

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Not in one click like a normal edit, no. The easiest solution is to move the page back to where you originally wanted it, and then add the "Delete" template to any redirect pages which were created in the process that you don't need any more.

PS: Another thing to note is that the "User:" namespace is typically reserved for actual wiki user pages (e.g. User:Space in my case), as having a page titled "User:Johnathan Nox Carter" would imply that there is an user account on the wiki with that user name, which there isn't. I could rename your user to "Johnathan Nox Carter" if you'd prefer to use that name on the wiki as well; just contact me or any other wiki sysop and we'll see what we can do.