Ubuntu Change default user when username has spaces

How would I write my command to make the command prompt reckognize the space in my username?

I'm trying to change the default user on my ubuntu system, but since my username has space in it, it creates some trouble.

I have both tried to use the back slash

C:\WINDOWS\system32>ubuntu1804 config --default-user Oskar\ B

And also use quotation marks

C:\WINDOWS\system32>ubuntu1804 config --default-user 'Oskar B'

Both of these return Error: 0x80070057 Incorrect parameter.

How do I avoid this?