为什么要从NEAR协议的账户中删除所有访问密钥？

删除账户中的所有访问密钥可以确保账户的安全性。下面是删除NEAR协议账户中所有访问密钥的代码示例：

const near = require('near-api-js');

// 创建一个NEAR协议连接
const nearConfig = {
    networkId: 'testnet',
    nodeUrl: 'https://rpc.testnet.near.org',
    walletUrl: 'https://wallet.testnet.near.org',
    helperUrl: 'https://helper.testnet.near.org',
    explorerUrl: 'https://explorer.testnet.near.org',
};

const nearAPI = near.nearAPI;
const provider = new nearAPI.providers.JsonRPCProvider(nearConfig.nodeUrl);
const nearMasterAccount = new nearAPI.Account(provider);

// 从NEAR协议账户中获取所有的访问密钥
async function removeAllAccessKeys(accountId) {
    const account = await nearMasterAccount.getAccount(accountId);

    for (let accessKey of account.accessKeys) {
        // 如果access_key字段中没有存储密钥，直接删除
        if (!accessKey.public_key) {
            continue;
        }
        // 否则就是存储了密钥，需要使用私钥进行签名
        const keyPair = nearAPI.utils.key_pair.KeyPair.fromString(process.env.MASTER_ACCOUNT_PRIVATE_KEY);
        const nonce = accessKey.nonce + 1;
        const actions = [
            nearAPI.transactions.deleteKey(accessKey.public_key, nonce),
        ];

        const deleteAction = nearAPI.transactions.createTransaction(
            accountId,
            keyPair.publicKey,
            actions,
            nearAPI.transactions.generateNonce(keyPair.publicKey, nonce),
        );

        await nearMasterAccount.signAndSendTransaction(accountId, [deleteAction], keyPair);
    }
}

removeAllAccessKeys('my_near_account');