如何从签约单据c#中移除不匹配的DocuSign通用模板锚字段？

using System;
using System.Collections.Generic;
using DocuSign.eSign.Api;
using DocuSign.eSign.Client;
using DocuSign.eSign.Model;

public class RemoveUnmatchedAnchors
{
    public void RemoveUnmatchedAnchorsFromDocument(string documentId)
    {
        // 设置DocuSign API的访问凭证
        string accessToken = "YOUR_ACCESS_TOKEN";
        string accountId = "YOUR_ACCOUNT_ID";

        // 创建DocuSign API客户端
        ApiClient apiClient = new ApiClient("https://demo.docusign.net/restapi");

        // 设置访问凭证
        apiClient.Configuration.DefaultHeader["Authorization"] = "Bearer " + accessToken;

        // 创建签约单据API实例
        EnvelopesApi envelopesApi = new EnvelopesApi(apiClient);

        try
        {
            // 获取签约单据的详细信息
            Envelope envelope = envelopesApi.GetEnvelope(accountId, documentId);

            // 获取模板ID和锚字段信息
            string templateId = envelope.TemplateId;
            List<Anchor> anchors = envelope.Recipients.Signers[0].Anchors;

            // 遍历锚字段列表，移除不匹配的字段
            for (int i = anchors.Count - 1; i >= 0; i--)
            {
                Anchor anchor = anchors[i];

                // 检查字段是否匹配所需的条件，这里假设字段名称为"FieldName"，并且需要移除不匹配的字段
                if (anchor.AnchorString != "FieldName")
                {
                    anchors.RemoveAt(i);
                }
            }

            // 更新签约单据，将更新后的锚字段列表重新提交给DocuSign API
            Recipients recipients = new Recipients();
            recipients.Signers = new List<Signer>();
            recipients.Signers.Add(new Signer { RecipientId = "1", Anchors = anchors });

            EnvelopeDefinition envelopeDefinition = new EnvelopeDefinition
            {
                TemplateId = templateId,
                Recipients = recipients
            };

            envelopesApi.Update(accountId, documentId, envelopeDefinition);
        }
        catch (Exception ex)
        {
            Console.WriteLine("Error: " + ex.Message);
        }
    }
}