If you need to stop a process (program), you can use the "taskkill" command in Windows.

Example:

taskkill /im processname.exe /f

You can also kill multiple processes at once that share similar names. Say you want to kill processname1.exe, processname2.exe, and processname3.exe running.

taskkill /im processname*.exe /f

For more detailed uses, check out Microsoft's TechNet article on it: http://technet.microsoft.com/en-us/library/bb491009.aspx.