Remove workflow field data

cd 'master:/sitecore/content/Corporate/Data'
Get-ChildItem . -Recurse | ForEach-Object {
    $_.Editing.BeginEdit()
    $_.Fields["__Style"].Value = $null
    $_.Fields["__Workflow state"].Value = $null
    $_.Fields["__Workflow"].Value = $null
    $_.Fields["__Default workflow"].Value = $null
    $_.Editing.EndEdit()
}