How to close any application even if task manager unable to close?

"You could try giving the taskkill command a shot:

taskkill /f /im program_name.exe

Although I believe it uses the same method to kill processes as Task Manager. Worth a shot though before reaching for the third party tools.

If you're interested in other programs, I've found that Sysinternals Process Explorer can sometimes kill things Task Manager can't. There is also a nifty tool called PsKill, which I've used to kill some processes that Task Manager wouldn't.

What processes are you trying to kill though? Windows will prevent you from killing certain services for stability reasons."