delete https://{accountName}.{environment}.com.br/api/checkout/pub/orderForm//customData//
Your account may create apps, which contain custom fields, through the Update orderForm configuration request. The value of a specific custom field can be removed by this request.
To do that, you need to inform in the URL the ID of the app you created with the configuration API (appId).
You also need to iform the specific field created in this app (identified by the appFieldName parameter, also passed through the URL) whose value you want to remove.