Currently timodule.xml in Windows module project is not used at all. But in order to align with how it's used in other platforms, we may need to have a way to specify target Windows sdk version attribute in it.
To be specific, to align with other platform attributes, it would be <uses-sdk targetSdkVersion="10.0" />.
When targetSdkVersion is specified, Windows module build should take the value as target Windows sdk version. Currently Windows 10 support is built by default whenever Windows 10 sdk is available, but you should be able to remove it by explicitly specifying 8.1 for it.
Then update timodule.xml to explicitly specify 8.1.
Then build the module and make sure packaged zip doesn't contain win10 folder in it.