This can be invoked in an un-elevated session. The command is:

taskkill /F /IM <PROGRAM.EXE>

Sample output:

PS C:\WINDOWS\system32> taskkill /F /IM iexplore.exe
SUCCESS: The process "iexplore.exe" with PID 14060 has been terminated.
SUCCESS: The process "iexplore.exe" with PID 41036 has been terminated.
SUCCESS: The process "iexplore.exe" with PID 12836 has been terminated.
SUCCESS: The process "iexplore.exe" with PID 40696 has been terminated.
SUCCESS: The process "iexplore.exe" with PID 26112 has been terminated.
SUCCESS: The process "iexplore.exe" with PID 3272 has been terminated.
SUCCESS: The process "iexplore.exe" with PID 80368 has been terminated.
SUCCESS: The process "iexplore.exe" with PID 52624 has been terminated.
SUCCESS: The process "iexplore.exe" with PID 23604 has been terminated.
SUCCESS: The process "iexplore.exe" with PID 34608 has been terminated.
SUCCESS: The process "iexplore.exe" with PID 37360 has been terminated.
SUCCESS: The process "iexplore.exe" with PID 23164 has been terminated.
SUCCESS: The process "iexplore.exe" with PID 29096 has been terminated.
SUCCESS: The process "iexplore.exe" with PID 59356 has been terminated.
SUCCESS: The process "iexplore.exe" with PID 56920 has been terminated.
SUCCESS: The process "iexplore.exe" with PID 79644 has been terminated.
SUCCESS: The process "iexplore.exe" with PID 58124 has been terminated.
SUCCESS: The process "iexplore.exe" with PID 16884 has been terminated.
SUCCESS: The process "iexplore.exe" with PID 54112 has been terminated.
SUCCESS: The process "iexplore.exe" with PID 75388 has been terminated.
SUCCESS: The process "iexplore.exe" with PID 3092 has been terminated.
SUCCESS: The process "iexplore.exe" with PID 38984 has been terminated.
SUCCESS: The process "iexplore.exe" with PID 76288 has been terminated.