Windows comes with a nice command line option that will allow you to close a process. The way I typically do this is as follows:
taskkill /f /im processtokill.exe
That closes the process according to the process name (under process tab in explorer). It force closes an application that is not responding pretty much instantly. How to do this on a remote computer?
taskkill /s computername /f /im processtokill.exe
*You may be required to put in username & password!!!