sdk-for-dart/docs/examples/project/update-auth-method.md

import 'package:dart_appwrite/dart_appwrite.dart';
import 'package:dart_appwrite/enums.dart' as enums;

Client client = Client()
    .setEndpoint('https://<REGION>.cloud.appwrite.io/v1') // Your API Endpoint
    .setProject('<YOUR_PROJECT_ID>') // Your project ID
    .setKey('<YOUR_API_KEY>'); // Your secret API key

Project project = Project(client);

Project result = await project.updateAuthMethod(
    methodId: enums.ProjectAuthMethodId.emailPassword,
    enabled: false,
);