Behavior: Removes the specified collection associations from each content item in the list. This does not delete the collections themselves, only the associations between collections and content items. Returns a batch result with per-item status.

Authorization: Requires a valid Bearer token.

Side Effects: Deletes collection-to-content association records.

Error Scenarios: Returns 400 if the input is null or the items list is empty. Returns 404 if the items list is null.