The description of the item here is unclear. However we can make a couple of inferences that should lead us to the solutions:
There is no statement that the items cannot be removed. D&D 4e is an exception based rules system. If there is no rule that says you can't then you probably can.
There is no indication that the items are consumed, in fact they can be used for the same purpose over and over and do not have to be refreshed. Implying that the armor merely reflects their properties, not consumes their effectiveness
Based on these assumptions then I'd say that it's possible to remove an item from the armor. However, that leaves us with the question of what kind of action it would be to remove the item. Since inserting them does not seem to be a combat action, I'd rule that you can take any item out while you are not in combat. If you remove the item that is currently giving the armor it's resistance then you will break that resistance. If one were to make the case that it is a combat action (perhaps by describing the device that contains the nodes) then a standard action would be reasonable (same action as stowing/equipping a shield).
An argument could be made, that since drawing and stowing (the word specifically used here) are classified as minor actions, that they remain minor actions with this armor. I'm not completely sold on this logic, but it's certainly a viable argument.
However (because the rules here are unclear), whether you can remove an item, in or out of combat (and what the effects are when you do), is pretty much left up to the DM here. You should work with her to determine what kind of action it is or if it is even possible.