Cannot map HKU registry hive with powershell

I have a question regarding deleting from registry key HKU (HKEY_USERS). If I run this with powershell, I get an error:

Invoke-Command -ComputerName $inputPC -ScriptBlock { Remove-Item -Path 'HKU:\S-1-5-25\Software\Microsoft\Windows\CurrentVersion\RunOnce'}

The error:

Cannot find drive. A drive with the name 'HKU' does not exist.
    + CategoryInfo          : ObjectNotFound: (HKU:String) [Remove-Item], DriveNotFoundException
    + FullyQualifiedErrorId : DriveNotFound,Microsoft.PowerShell.Commands.RemoveItemCommand
    + PSComputerName        : clt64792

But if for HKU: I exchange it for example to HKLM: it works and deletes the registry key, how can I access the HKU? I have tried different approaches to delete registry keys and all work the same, but none of them maps the HKU registry key.

Solution

By default, only the following PowerShell drives referencing registry locations are defined:

PS> Get-PSDrive -PSProvider Registry

Name           Used (GB)     Free (GB) Provider      Root                                                                                                           CurrentLocation
----           ---------     --------- --------      ----                                                                                                           ---------------
HKCU                                   Registry      HKEY_CURRENT_USER                                                                                                             
HKLM                                   Registry      HKEY_LOCAL_MACHINE

That is, only drives HKCU: and HKLM: exist by default.

In order to access keys in the HKEY_USERS hive, you have two options:

Either: Define a custom HKU PowerShell drive using New-PSDrive, as theadzik suggests in a comment, though that may not be worth it (in your case, you'll have to do that inside the script block passed to Invoke-Command):

# Define drive HKU:
New-PSDrive -PSProvider Registry -Name HKU -Root HKEY_USERS
# Now you can use HKU:\... paths

Or: Use provider prefix registry:: with the native registry path, which is simpler for ad-hoc use:

# E.g.
Get-ChildItem registry::HKEY_USERS\.DEFAULT

In the context of your command:

Invoke-Command -ComputerName $inputPC -ScriptBlock { 
  Remove-Item 'registry::HKEY_USERS\S-1-5-25\Software\Microsoft\Windows\CurrentVersion\RunOnce'
}