Can someone explain this?

[FCIN]

For MOW in the GN rulebook it has a rule that states that if Torpedos are placed and the protection is no longer required they are to be removed. If you have a rulebook from your railroad it may have some rule governing it

That makes sense for MOW gangs who would be protecting themselves on short sections of track. None of the rule books that I have including the Uniform Code of Operating Rules has any provision for a train to remove them. Just wouldn't be practical or safe.