code: public void deleteCustomField(String accountId, String customFieldId, AccountsApi.DeleteCustomFieldOptions options) throws ApiException {
      Object localVarPostBody = "{}";
      
        // verify the required parameter 'accountId' is set
        if (accountId == null) {
        throw new ApiException(400, "Missing the required parameter 'accountId' when calling deleteCustomField");
        }
      
        // verify the required parameter 'customFieldId' is set
        if (customFieldId == null) {
        throw new ApiException(400, "Missing the required parameter 'customFieldId' when calling deleteCustomField");
        }
      
      // create path and map variables
      String localVarPath = "/v2/accounts/{accountId}/custom_fields/{customFieldId}".replaceAll("\\{format\\}","json")
        .replaceAll("\\{" + "accountId" + "\\}", apiClient.escapeString(accountId.toString()))
        .replaceAll("\\{" + "customFieldId" + "\\}", apiClient.escapeString(customFieldId.toString()));
  
      // query params
      java.util.List<Pair> localVarQueryParams = new java.util.ArrayList<Pair>();
      java.util.Map<String, String> localVarHeaderParams = new java.util.HashMap<String, String>();
      java.util.Map<String, Object> localVarFormParams = new java.util.HashMap<String, Object>();
  
      if (options != null) {
         localVarQueryParams.addAll(apiClient.parameterToPairs("", "apply_to_templates", options.applyToTemplates));
      }
      
      
        final String[] localVarAccepts = {
      "application/json"
        };
        final String localVarAccept = apiClient.selectHeaderAccept(localVarAccepts);
  
        final String[] localVarContentTypes = {
      
        };
        final String localVarContentType = apiClient.selectHeaderContentType(localVarContentTypes);
  
        String[] localVarAuthNames = new String[] { "docusignAccessCode" }; //{  };
  
  
        apiClient.invokeAPI(localVarPath, "DELETE", localVarQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAccept, localVarContentType, localVarAuthNames, null);
        }
docs: Delete an existing account custom field.
  
  @param accountId The external account number (int) or account ID Guid. (required)
  @param customFieldId  (required)
  @param options for modifying the method behavior.
  @throws ApiException if fails to make API call