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There are 2 ways to do so. One is to go to Add or Remove Programs, select “show updates”, and you can uninstall it.
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The other one is to go to C:\WINDOWS\$NtUninstallKB926139$\spuninst, double click spuninst.exe, and then you can uninstall it. You can also use the command line to uninstall Windows Powershell as follows:
C:\WINDOWS\$NtUninstallKB926139$\spuninst\ spuninst.exe /q
After the upgrade, Windows Powershell is not installed on windows Vista / Windows Server 2008. If you still need it, you need to install it again.
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For Windows Vista, you need to download Windows Powershell Vista version in Microsoft website.
For Windows Server 2008, Windows Powershell is part of the windows components. You can see use the following command line to install it.
ServerManagerCmd.exe /install PowerShell
Do you think Windows Powershell is an interesting issue?