Предлагаю вашему вниманию код своего .cmd файла для удаления WinRAR в домене посредством GPO:
Код:

if exist "%ProgramFiles%\WinRAR\uninstall.exe" start "" /wait "%ProgramFiles%\WinRAR\uninstall.exe" /s
if exist "%ProgramFiles(x86)%\WinRAR\uninstall.exe" start "" /wait "%ProgramFiles(x86)%\WinRAR\uninstall.exe" /s
REG DELETE "HKCR\Applications\WinRAR.exe" /f
REG DELETE "HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\MenuOrder\Start Menu2\Programs\WinRAR" /f
REG DELETE "HKCU\Software\Microsoft\Windows\ShellNoRoam\MUICache" /v "C:\Program Files\WinRAR\uninstall.exe" /f
REG DELETE "HKCU\Software\Microsoft\Windows\ShellNoRoam\MUICache" /v "C:\Program Files\WinRAR\WinRAR.exe" /f
REG DELETE "HKCU\Software\WinRAR" /f
REG DELETE "HKCU\Software\WinRAR SFX" /f
REG DELETE "HKLM\SOFTWARE\Classes\Applications\WinRAR.exe" /f
REG DELETE "HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.rar\OpenWithProgids" /v WinRAR /f
REG DELETE "HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.zip\OpenWithProgids" /v WinRAR /f
REG DELETE "HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.cab\OpenWithProgids" /v WinRAR /f
REG DELETE "HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.arj\OpenWithProgids" /v WinRAR /f
REG DELETE "HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.gzip\OpenWithProgids" /v WinRAR /f
REG DELETE "HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.uue\OpenWithProgids" /v WinRAR /f
REG DELETE "HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.bz2\OpenWithProgids" /v WinRAR /f
REG DELETE "HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.jar\OpenWithProgids" /v WinRAR /f
REG DELETE "HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.iso\OpenWithProgids" /v WinRAR /f
REG DELETE "HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.z\OpenWithProgids" /v WinRAR /f
Возможно кому-то понадобится. Протестировал на XP и 7.