This application is able to switch WiFi tethering via bluetooth on Android devices where similar application is installed.
Unfortunately Universal Windows Application API does not provide any way to switch WiFi tethering. Only swithching on remote Android device is possble.
MS Store link https://www.microsoft.com/store/apps/9NBLGGH4WFDC
Google Play store link https://play.google.com/store/apps/details?id=com.azi.tethermote
Android Tethermote repository https://github.com/Rambalac/Tethermote