If there is a trailing space in the name of the output folder then that space is created in the folder name in the file system. Windows is unable to deal with that extra space in the GUI and the result is a folder that can't be deleted, renamed, or otherwise modified from the GUI.
I have determined that the folder can be deleted by using a special "Unicode" formatted command line.
It would be helpful if the application trimmed the trailing space before creating the folder. I have screenshots but the board won't allow me to upload them--"Sorry the board attachment quota has been reached".