Hi,
Ever since premium consumables were removed from the game, consumables are free and not demountable. Even when you have a slot with a selectable consumable, one of them is always mounted:
Signals, economic bonuses and expendable camos are 'consumed' only when you enter battle, they do not get removed from inventory when you mount them, so there's no need for a demount all mod.
BUT, I assume you asked for the demount all mod because in Port you cannot see what is mounted on your ship or how many of these items are left in your inventory or if Auto-purchase is enabled for camos or economic bonuses so it would be safer knowing that all of these items were removed. There is however a solution to that problem, it is Carousel Extended. You can see and change your ship's config right in Port before you click Battle!
Cheers!