Hi apassaro,
If you want to kill a task on windows,
1-) Identify the "app name" for instance => "calc.exe"
2-) Open command prompt by Clicking Start->Run+type cmd.exe in the text input (Enter)
3-) On the command prompt type
taskkill /f /im [Application Image Name]
on my case
taskkill /f /im calc.exe
After that you should be able to forcefully close the app.
Thanks
Said Samadli
Senior Software Engineer