So -- one of those is named "Test" & the other is named "Test.whatever"? I presume the latter is the one you generally use. To know for sure which one you are using -- it's the one whose Remove button won't light up in NETPLWIZ when selected. I was expecting to see a 3rd with a fit & proper name on it. And I expected the 3rd would be the one you normally used.
(1) The name isn't really important, actually -- but it would be nice to have one without the word "test" in it. However, it's a ton of trouble to rename one of those. I can't quite recommend it...
https://www.tenforums.com/tutorials/89060-change-name-user-profile-folder-windows-10-a.html
How to Change the Name of a User Profile Folder in Windows 10
The article has dire warnings in it. Might be best not to try it.
(2) The only other way is make a new User Profile with a new name that you like. But you lose the settings & some installations that were done in the current profile. It's a ton of trouble to move them over. I can't quite recommend this either.
To get an idea how things will initially look/work in a new profile, "right-click START, Shut down or sign out, Sign out". Then sign in to the other.
(3) Maybe it's actually best to let it all alone, like you prudently decided a day/so ago. Actually, having two Administrator accounts is a good thing. If one ever dies, you'd have the other to attempt repairs. Also, you can see in that Brink article, some procedures do require the use of a 2nd Administrator to accomplish.