Basically Microsoft store does not allow you to unistall or disown your app, that you installed. You cannot find it in the programs section of the control panel nor in the microsoft store .
You can only uninstall it either in the apps section from the settings menu in windows 8 and above.
It can also be directly from the start menu, the app is pinned to it by just right clicking it and clicking on uninstall.
AV's Blog 