Press Alt + F4 while the app is active
Press Ctrl + Shift + Esc to open Task Manager
Find the app under Processes
Select the app
Click End task
Press Ctrl + Alt + Delete
Open Task Manager
Find the app
Select it
Click End task
Open Command Prompt as administrator
Run tasklist to find the app process name
Run taskkill /F /IM appname.exe
Run taskkill /F /PID processid
Restart Windows if the app still will not close