Remove-Computer

Remove the local computer from a workgroup or domain.

Syntax
      Remove-Computer [[-Credential] PSCredential] [-Force] [-PassThru]
         [-Confirm] [-WhatIf] [CommonParameters]

Key
   -Credential PSCredential
       A user account that has permission to perform this action.
       The default is the current user.

       Type a user name, such as "User64" or "Domain64\User64", or enter a
       PSCredential object, such as one generated by Get-Credential.
       If you type a user name, you will be prompted for a password.

       To remove a computer from a domain, you must use -Credential, even 
       when using the credentials of the current user.

    -Force
       Override any restrictions that would prevent the command from succeeding,
       apart from security settings.

    -PassThru
       Return the results of the command. Otherwise, this cmdlet does not generate any output.

   -confirm
       Prompt for confirmation before executing the command.

   -whatIf
       Describe what would happen if you executed the command without actually
       executing the command.

   CommonParameters:
       -Verbose, -Debug, -ErrorAction, -ErrorVariable, -WarningAction, -WarningVariable,
       -OutBuffer -OutVariable.

Remove-Computer removes the local computer from its current workgroup or domain.

When a computer is removed from a domain, Remove-Computer will also disable the computer's domain account.

Restart the computer to make the change effective.

Use the -Verbose and -PassThru parameters to view the results of the command.

Examples

Remove the local computer from the domain to which it is joined:

PS C:> remove-computer -credential domain64\admin64 -passthru -verbose; restart-computer

“No amount of time can erase the memory of a good cat, and no amount of masking tape can ever totally remove his fur from your couch” ~ Leo F. Buscaglia

Related:

Add-Computer - Add a computer to the domain
Restart-Computer - Restart the operating system on a computer