After uploading, you can set various things on the world's homepage. It's standard Steam Workshop stuff, if something is not clear, you should look for help with the Steam Workshop.
As Catacomber said, you can find your stuff in Steam under the "Content" menu point.
But to access a world's page, just load it in the editor, then select "File / Open the world's page in Steam".
For your particular worlds:
You set "Terror's Returnal" to either "Friends-only" or "Hidden". When you upload, the default is "Public", so you must have set it by hand... In any case, you can set it on the world's homepage, in the "Owner controls" box (on the right side), under "Change Visibility".
Also, I think it would be best if you deleted all the other empty worlds you've created. Just select them and you'll find a "Delete" control in the same "Owner controls" box.