This should do it:
Funtion provided by @Andrew_Lambert on this forum here:
Function KillShell(sh As Shell) As Integer
#if TargetWindows Then
Declare Function TerminateProcess Lib "Kernel32" (ProcessHandle As Integer, ExitCode As Integer) As Boolean
Declare Function GetLastError Lib "Kernel32" () As Integer
If TerminateProcess(sh.PID, 0) Then
Return GetLastError()
End If
#else
sh.close
#endIf
End Function
Modified to be cross platform