翻译成英语 ：对于需要报废的机器,一定要得到上级的批准.

对于需要报废的机器,一定要得到上级的批准.Approval of higher authority should be obtained for any machines to be scrapped.
更为庄重的说法是：
No machine should be discarded until the approval of superior authority has been given.
注：在合同,规范,法律英语中,should,shall 就表示必须.,应该.,所以没有用must