Unable to change WSL 2 to WSL 1. A version number could not be parsed

I installed WSL using the command

wsl --install

This installed default Ubuntu using WSL 2. Now I find WSL 2 is slow for file access cross NTFS files. And I read the WSL 1 is faster for file IO when using Linux tools that needs to access NTFS files (i.e. /mnt/g for example, where G: is NTFS).

But I am not able to change the installed Ubuntu back to WSL 1. Here is what I tried

Windows PowerShell
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C:Windowssystem32> wsl --set-default-version Ubuntu 1
A version number could not be parsed.

C:Windowssystem32> wsl -l -v
  NAME      STATE           VERSION
* Ubuntu    Stopped         2

C:Windowssystem32> wsl --set-default-version "Ubuntu" 1
A version number could not be parsed.

C:Windowssystem32> wsl --set-default-version 1
The operation completed successfully.

But it did not change

C:Windowssystem32> wsl -l -v
  NAME      STATE           VERSION
* Ubuntu    Stopped         2

I also rebooted the PC. I am also running all the above inside pwoershell.exe as Admin.

I am running windows 10 professional. version 21H1 OS build 19043.1620

Any suggestions how to change back to WSL 1 hopefully without having to remove current Ubuntu since I spend lots of time installing Linux software on it since then.