We do an uninstall using the code from the registry. For example, here's one I pulled from my laptop:
"C:\Program Files\Common Files\Microsoft Shared\OFFICE14\Oarpmany.exe" /removereleaseinpatch "{90140000-0011-0000-1000-0000000FF1CE}" "{0F6C4F72-6084-437B-9B35-F59B09E3C1B0}" "1033" "0"
We test beginning with this command line and modify as necessary. This particular one is from HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall, but I believe only 32-bit updates will appear there. For my 64-bit system, the remaining items are found here:
HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\Uninstall\{8E34682C-8118-31F1-BC4C-98CD9675E1C2}.KB2416472
Sample UninstallString value from this key:
c:\Windows\Microsoft.NET\Framework64\v4.0.30319\SetupCache\Extended\setup.exe /uninstallpatch {3162617C-537F-3BB6-8D0C-C6021F442391} /parameterfolder Extended