回复：请问863211关于cancel 140 的问题

Here is a follow up question. 再什么情况下原工作单位会cancel 140？
-It is up to the employer and it is not required by law. Some employers do not care about it and may never cancel the I-140 even if the employee has left.

要follow 什么程序才能 cancel？
-The employer just need to write a letter to USCIS to request the cancelation/withdrawl of the approved I-140.