If you for some reason should not want Internet Explorer 9 beta installed anymore, and can not uninstall Internet Explorer 9 Beta through Installed Updates in Programs and Feature in the Control Panel you can use the following command line:

FORFILES /P %WINDIR%\servicingPackages /M Microsoft-Windows-InternetExplorer-\*9.\*.mum /c "cmd /c echo Uninstalling package @fname && start /w pkgmgr /up:@fname /norestart"

Must be run be run with elevated local administrator rights.