This wont use the Installer for InfoPen this will use the MSI Installer to uninstall InfoPen.
Click Start > Run > Copy the following text and paste it in the run command.
code:
MsiExec.exe /X{ECE6DE3F-5E70-4CEC-A583-F7BF9E252A77}
Press ok
This will ask if you want to uninstall InfoPen say yes and the MSI Installer will uninstall it for you