remove-computer cmdlet access denied - powershell

Question

I am trying create a script to remove a computer from a domain using remove-computer -unjoincredentials domain\admin -passthru However, I consistently receive an error stating that
remove-computer : Failed to unjoin computer 'web140127105714' from domain 'domain.com' with the following error
message: Access is denied.
At line:1 char:1
+ remove-computer -UnjoinDomainCredential domain\admin -PassThru
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : OperationStopped: (web140127105714:String) [Remove-Computer], InvalidOperationException
+ FullyQualifiedErrorId : FailToUnjoinDomain,Microsoft.PowerShell.Commands.RemoveComputerCommand
The account I am using is a domain administrator with full access. I have confirmed that the account can manually unjoin from the domian.

Answer 1

Some operations on the console require you to be on an elevated PowerShell session. You can start your PowerShell session as Admin by right clicking on it and choosing 'Run as Administrator'. Then run the remove-computer cmdlet in that console session. Default title of the Administrator PowerShell console is 'Administrator : Windows PowerShell'. You can identify the window that way

Answer 2

Sounds like the OP found his answer, so here is a powershell self elevating example for future readers. Add to the top of your scripts and it will re-launch itself elevated so we don't have to right click and 'Run As Administrator'.
$WID=[System.Security.Principal.WindowsIdentity]::GetCurrent();
$WIP=new-object System.Security.Principal.WindowsPrincipal($WID);
$adminRole=[System.Security.Principal.WindowsBuiltInRole]::Administrator;
If ($WIP.IsInRole($adminRole)){
}else {
$newProcess = new-object System.Diagnostics.ProcessStartInfo 'PowerShell';
$newProcess.Arguments = $myInvocation.MyCommand.Definition
$newProcess.Verb = 'runas'
[System.Diagnostics.Process]::Start($newProcess);Write-Host 'Prompting for Elevation'
exit
}
#####################
# Add Scripts Below #
#####################
Write-Host 'ElevatedCodeRunsHere';
Write-Host 'Press any key to continue...'
$null = $Host.UI.RawUI.ReadKey('NoEcho,IncludeKeyDown')
Powershell start-process script calls a second script - how to make one script only

Answer 3

There is no such parameter as -unjoincredentials
http://technet.microsoft.com/en-us/library/hh849816.aspx