Remove Selected Shipping Rate from Quote
Removes the current shipping method associated with a specific quote based on the provided `quoteId`.
<Warning>This endpoint uses `/shipping-rate` (singular). Don't confuse it with the [Get Available Shipping Rates for a Quote](#get-rfq-quote_id-shipping-rates) endpoint, which uses `/shipping-rates` (plural). Using the wrong URL returns a **405 - Method Not Allowed** error.</Warning>