您可以创建类似下面的方法，您需要将其上传到Firebase Cloud Function上
第一个参数为：// 2小时（以毫秒为单位）。

exports.deleteOldMessages = functions.database.ref('[path]').onWrite(async (change) => {
    const ref = change.after.ref.parent; // reference to the parent
    const now = Date.now();
    const cutoff = (now - CUT_OFF_TIME) / 1000; // convert to seconds
    const oldItemsQuery = ref.orderByChild('seconds').endAt(cutoff);
    const snapshot = await oldItemsQuery.once('value');
    // create a map with all children that need to be removed
    const updates = {};
    snapshot.forEach(child => {
        updates[child.key] = null;
    });
    // execute all updates in one go and return the result to end the function
    return ref.update(updates);
});

您也可以查看下面的链接以供参考。
souce