procedure KillProcess(hWindowHandle: HWND);
var
  hprocessID: INTEGER;
  processHandle: THandle;
  DWResult: DWORD;
begin
  SendMessageTimeout(hWindowHandle, WM_CLOSE, 0, 0,
    SMTO_ABORTIFHUNG or SMTO_NORMAL, 5000, DWResult);
  if isWindow(hWindowHandle) then
  begin
    { Get the process identifier for the window}
    GetWindowThreadProcessID(hWindowHandle, @hprocessID);
    if hprocessID <> 0 then
    begin
      { Get the process handle }
      processHandle := OpenProcess(PROCESS_TERMINATE or PROCESS_QUERY_INFORMATION,
        False, hprocessID);
      if processHandle <> 0 then
      begin
        { Terminate the process }
        TerminateProcess(processHandle, 0);
        CloseHandle(ProcessHandle);
      end;
    end;
  end;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  // Finalizando o bloco de notas
  KillProcess(FindWindow('notepad',nil));
end;