Since W2K3 SP2 is an update to W2K3 SP1, if you install Powershell on W2K3 SP1 and upgrade to W2K3 SP2, to uninstall PowerShell you first have to uninstall W2K3 SP2.
You can read the whole post here: Windows Server 2003 SP2 upgrade. When I first went to install a pre-release version I went to Add/Remove Programs and couldn't find PowerShell, though I knew I had installed it. So I looked it up and realized it was an OS update. I didn't think much of it then other than to say, "How odd." Now, apparently, that approach isn't without its issues. So if you want to uninstall PowerShell, be aware that once you apply SP2 you're going to have to uninstall it first before you can uninstall PowerShell.
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