In short ... DON'T!

Assume that your distro's are locked away behind a one-way wall - Linux can see Windows files, but Windows cannot (safely) use Linux files. More details here: https://blogs.msdn.microsoft.com/commandline/2016/11/17/do-n...

And yes, we're working to close this gap in future releases, so stay tuned!

Be careful what you mess with in Windows regarding these folders. The WSL does not react as one might expect to changes made to its files using Windows (ie you can easily screw it up and have to in reinstall if you make changes to important WSL files via Windows).

The folder for WSL Ubuntu is usually here:

C:\Users\<username>\AppData\Local\Packages\CanonicalGroupLimited.UbuntuonWindows_79rhkp1fndgsc\LocalState

Your root directory should be here:

C:\Users\<username>\AppData\Local\Packages\CanonicalGroupLimited.UbuntuonWindows_79rhkp1fndgsc\LocalState\rootfs