How to revert this registry change, steam big picture added to ntuser.dat

[Sizzle]

I found this script and now cannot undo it. I tried del and delete but neither works. Also tried searching for the ntuser.dat but I can´t find it.

%WINDIR%\System32\reg.exe load HKLM\DefaultUser C:\Users\Default\NTUSER.DAT
%WINDIR%\System32\reg.exe add HKLM\DefaultUser\Software\Microsoft\Windows\CurrentVersion\Run /v SteamBigPicture /d "\"C:\Program Files (x86)/Steam/Steam.exe/" -bigpicture"
%WINDIR%\System32\reg.exe unload HKLM\DefaultUser

[76561198258988800]

Load the CURRENT_USER registry hive in regedit.exe and delete it from there.