What is defaultuser0 and is it safe to delete?

Solution 1:

What is defaultuser0?

After upgrading to the Anniversary Update, many users have noticed that apart from their regular user accounts, the OS also creates a new Defaultuser0 account. The most interesting part is that this unusual profile cannot be deleted even after performing a clean install.

The Defaultuser0 account bug has been haunting Windows users for a long time. Nobody knows exactly why this account is being created or how users can prevent its creation. The commonly accepted hypothesis suggests the Defaultuser0 profile is created when something goes wrong during the profile creation phase of the main account, and it should be harmless.

Source Windows 10 Anniversary Update is creating “defaultuser0” profiles

Is it safe to delete it?

Yes. Use one of the following methods.

How to get rid of the Defaultuser0 profile

Solution 1 – simply delete the Defaultusers0 account

Go to Control Panel > User accounts > Delete the profile

Solution 2 – Enable the hidden admin account

• Start your computer using your Windows 10 DVD or USB
• Select the correct time and keyboard type
• Click on Repair your computer
• Select Choose an option > Troubleshoot
• Click on Command Prompt > type the command net user administrator /active:yes
• Restart your computer > delete the Defaultuser0 account.

Source Windows 10 Anniversary Update is creating “defaultuser0” profiles

Solution 2:

Adding to @DavidPostill's answer:

Since, as noted in the comments, defaultuser0 does not show up in any graphical interfaces accessible through either the settings app or the control panel, here is how to get rid of it cleanly:

1. Run the Windows command prompt as Administrator

   • Option A: Rightclick on the cmd shortcut in the start menu and select "run as administrator"

   • Option B: Hold CRTL+SHIFT and click on any cmd shortcut or the executable itself

   • Option C: Open the task manager, selet file -> new task, enter "cmd" and select the run as administrator checkmark

2. Enter net user defaultuser0 /DELETE

Solution 3:

Seems like this potentially was hooked by NT Authority\System or NT Service\TrustedInstaller:

1. Start a console as Administrator or a member of Administrators-group.
2. Type in psexec -s -i cmd.exe followed by ENTER.
3. Type in lusrmgr.msc followed by ENTER.
4. Remove defaultuser0 in Local Users and Groups /Users.

Of course this means loading the PsTools beforehand and placing them into %systemroot%\System32.