# Remove one-time product from upcoming order

Removes a previously added one-time product (one-off) from a specific upcoming billing attempt. This allows customers or merchants to cancel add-on items before the order is processed.

Key Features:
- Flexible Cancellation: Remove add-ons before order processes
- Targeted Removal: Remove specific variant from specific order
- No Subscription Impact: Doesn't affect recurring items
- Customer Control: Let members manage their add-ons
- Activity Logging: Tracks removal for audit trail

Required Parameters:
- Contract ID: Target subscription contract
- Billing Attempt ID: Order to remove item from
- Variant ID: Product variant to remove

How It Works:
1. Validates contract exists and belongs to shop
2. Finds one-off matching contract, billing attempt, and variant
3. Deletes the one-off record
4. Returns updated list of remaining one-offs
5. Logs removal activity for audit trail

Use Cases:
- Customer changes mind about add-on product
- Remove out-of-stock items from upcoming orders
- Cancel promotional items no longer available
- Customer wants to reduce order total
- Merchant corrects mistakenly added items
- Manage add-ons in customer portal

Business Rules:
- Can only remove from upcoming (unprocessed) orders
- Must match exact contract, billing attempt, and variant
- Returns remaining one-offs after deletion
- Cannot remove from past/completed orders

Authentication: Requires API key authentication via X-API-Key header or api_key parameter

Endpoint: DELETE /api/external/v2/subscription-contract-one-offs-by-contractId-and-billing-attempt-id
Version: 0.0.1

## Query parameters:

  - `api_key` (string)
    API Key (Deprecated - Use Header X-API-Key instead)

  - `contractId` (integer, required)
    Subscription contract ID
    Example: 123456

  - `billingAttemptId` (integer, required)
    Billing attempt ID to remove the item from
    Example: 789012

  - `variantId` (integer, required)
    Product variant ID to remove
    Example: 456789

## Header parameters:

  - `X-API-Key` (string)

## Response 200 fields (application/json):

  - `id` (integer)

  - `shop` (string, required)

  - `billingAttemptId` (integer)

  - `subscriptionContractId` (integer)

  - `variantId` (integer)

  - `variantHandle` (string)

## Response 401 fields (*/*):

  - `id` (integer)

  - `shop` (string, required)

  - `billingAttemptId` (integer)

  - `subscriptionContractId` (integer)

  - `variantId` (integer)

  - `variantHandle` (string)

## Response 403 fields (*/*):

  - `id` (integer)

  - `shop` (string, required)

  - `billingAttemptId` (integer)

  - `subscriptionContractId` (integer)

  - `variantId` (integer)

  - `variantHandle` (string)

## Response 404 fields (*/*):

  - `id` (integer)

  - `shop` (string, required)

  - `billingAttemptId` (integer)

  - `subscriptionContractId` (integer)

  - `variantId` (integer)

  - `variantHandle` (string)


## Response 400 fields