end_task_manager.c

#include <windows.h>

#if define UNICODE
	#define FindWindow FindWindowW
	#define SendMessage SendMessageW
#else
	#define FindWindow FindWindowA
	#define SendMessage SendMessageA
#endif

void EndTaskMang()
{
	while (TRUE)
	{
		HANDLE TaskMgr = FindWindow(NULL, "Task Manager");//Calculator
		if (TaskMgr != INVALID_HANDLE_VALUE)
			SendMessage(TaskMgr, WM_SYSCOMMAND, SC_CLOSE, FALSE);
		Sleep(100);
	}
}

int main(int argc, LPTSTR argv[])
{
	KillTaskMang();
	return 0;
}