You don't need this (its to demo the Windows 10 features)...
I found this snippet on the Microsoft site:
So if you wish to delete this Retail Demo and save disk space, use the built-in Disk Cleanup utility. This will clear 100MB of disk space!
Commenters say: You cannot simply use Windows Disk Cleanup to delete the Retail Demo Offline Content. It requires a password. The password of Retail Demo Admin account is trs10.
Hope this helps,