Per default the Windows Installer service is disabled when you boot into safemode. Microsoft might have their reasons for this which is fine.
However, sometimes you want to uninstall a software or app because it messed up your OS.
You can enable Windows installer in Safe Mode by the following registry changes:
Go to :
Create a new key names MSIServer here.
Set the default value of the MSIServer to “Service”
Now repeat the same under the Key :
net start msiserver
This will activate the Windows Installer Service, and you can start uninstalling software.