Shopify Ajax API – /cart/update.js not working to update product quantity

I’m trying to remove a product from the cart using the Shopify Ajax API, but the product isn’t getting removed and I get an Unexpected token: ':'
error in the console.

$(".slide-cart-remove").on("click", function() {
    var id = $(this).attr("id");
    jQuery.post('/cart/update.js', {updates: {id: 0}});
});

On the click of the “remove” button, I’m calling the API to update its quantity to 0. The “remove” button’s ID is the variant_id of the product I’m trying to remove, which is why I’m passing it.

This is how I give it the same ID as the variant_id, if it makes any difference:

$(productRemove).attr("id", data.items[i].variant_id);

Is there something I’m missing in the syntax?

EDIT: As mentioned below, I tried changing the syntax to this:

jQuery.post('/cart/update.js', {quantity: 0, id: varId});

However, it still doesn’t seem to work. (note that the varId variable contains a real variation ID of a product that is in the cart)