Can the Tower of the Hand Eddard cancel the effects of Marched to the Wall?

Nope. The reason being is that the effect on marched to the wall is not a triggered effect. Its a passive. In order for something to be a triggered effect it needs to have the bold word in front. So something like Response: or Any Phase: or Challenges:

Plus, Marched chooses more than one character. Eddard can only cancel effects that choose the Noble as the only target of the effect. That's probably not going to happen with Marched most of the time.