Updating Order Line Items via REST API doesn't remove existing Line Items

[databuzz]

I'm using WooCommerce 3.5.2 and the REST API v2. I have created an Order successfully with 2 line items:

"id": 3583,
"line_items": [
{
"id": 95,
"meta_data": [],
"name": "Happy Ninja",
"price": 50,
"product_id": 37,
"quantity": 2,
"sku": "",
"subtotal": "100.00",
"subtotal_tax": "10.00",
"tax_class": "",
"taxes": [
{
"id": 1,
"subtotal": "10",
"total": "10"
}
],
"total": "100.00",
"total_tax": "10.00",
"variation_id": 0
},
{
"id": 107,
"meta_data": [],
"name": "Calligraphy Set",
"price": 89,
"product_id": 1098,
"quantity": 1,
"sku": "",
"subtotal": "89.00",
"subtotal_tax": "8.90",
"tax_class": "",
"taxes": [
{
"id": 1,
"subtotal": "8.9",
"total": "8.9"
}
],
"total": "89.00",
"total_tax": "8.90",
"variation_id": 0
}
],

I then do a PUT to /wp-json/wc/v2/orders/3583 with just one line item:

"id" : 3583,
"line_items" :
[
{
"id" : "107",
"name" : "Calligraphy Set",
"product_id" : "1098",
"quantity" : 1,
"subtotal" : "89.00",
"total" : "89.00",
"variation_id" : "0"
}
],

but it doesn't delete the 2nd line item (id 95) it simply adds an additional line item. I've tried updating the Order with no line items as well:

"id" : 3583,
"line_items" : [],

but that doesn't remove the line items. I would have thought if I didn't pass in the ID it would remove the existing line items from the Order?

[rrennick]

To delete the second item add {"id":95,"quantity":0}.

[ThomasVeld]

This is likely because of your order status, you can't remove products from processing / completed orders. With pending orders this is possible.