Is it ok to allow Steppers or incremental buttons to remove items?

Question

I read sometime ago that it is bad UX if the system allows the user to remove an item (for example, form their cart) if he uses numeric steppers down to 0. Should the system allow this or stop at 1 as the minimum amount and have another button to remove the item?

EDIT:

This is a mobile app so it would be within user's expectations that the items should update automatically. Expecting the user to refresh their cart every time doesn't feel that right to me... Also my users are mostly elder and/or sick people.

This stepper function is being implemented in a product carousel in the main page to add items to the cart AND in the cart. Below every item in the carousel there's an "Add to cart" button which after being pressed turns into the incremental steppers. Some users didn't have a problem to add items, set an amount and then going to the cart to make further changes if later on they decided to do so. However someone mentioned that they might have added the item by mistake while viewing the carousel and wanted it removed without having to go to their cart to do so. That raised the question whether changing the quantity to zero should also remove the item. In the cart there's also a "remove item" button but I'm unsure on how to proceed with the carousel without adding more complexity.

Answer 1

Here is an article from Baymard Institute: Shopping Cart: Auto-Update User’s Quantity Changes and Allow ‘Quantity 0’ (86% Don’t)

“I tried minus because I thought you could get it down to zero.” A test subject tried to remove a product by subtracting from the quantity in an attempt to set it to 0. Many users have the expectation that setting a product’s quantity to 0 will effectively remove the item from their cart.

So, use auto-update, allow selection of "0", but also provide a button to "Remove".

Answer 2

I would allow setting a quantity 0 to remove an item because it is the obvious intent of having a quantity of 0. It seems that disallowing 0 could be an implementation issue where enforcing a minimum quantity could be easier than calling a deletion function for 0. It might also be a ploy to attempt to force customers to keep items in their carts for later purchase.

However, I would not make setting a quantity of 0 the only way to remove an item from a cart.

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For those who do not read carefully, I do not state that items should be removed immediately upon setting the value to 0.

Answer 3

Looking more at the UI aspect of this...

Like other answers, I would allow setting a quantity of zero (either through clicking up/down buttons, or explicitly typing 0) to mean "remove from my cart", but I wouldn't immediately remove the actual item-line (whereas you might immediately remove the item line if an explicit Remove from cart button was used¹).

Instead, I would probably leave the entry in place with a quantity of zero (perhaps until a "natural" refresh were to redraw the page), possibly greying-out most of the line (except the quantity selection elements, which would remain active should you want to restore the item to your cart).

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¹ Explicitly clicking on a "Remove" button could either just delete the entry, might seek confirmation, or might replace the entry with something along the lines of "Item removed... click to restore" element. Although there's not much physical difference between clicking a "Remove" button and clicking a stepper to reduce the quantity to zero, it feels "wrong" to remove the entry in the latter case, even if you were to replace it with a "Click to restore" element. Possibly because if you were intending to reduce the quantity from 2 to 1, it is easier to mis-click and reduce it to zero by accident.