删除旧值

Question

我有一个控制实体日志的mongo集合。 我想删除旧实体：

{
    "_id" : ObjectId("5a3bf52aa0195f5dd63ff96e"),
    "firstName" : "name17",
    "email" : "email17@gamail.com",
    "recovery" : {
        "token" : "afcc9f4d-3fd5-4fa4-a48b-402f7eea07da",
        "updatedAt" : ISODate("2017-12-21T17:53:46.710Z"),
        "createdAt" : ISODate("2017-12-21T17:53:46.710Z")
    },
    recoveryAttempts: [{
        "token" : "afcc9f4d-3fd5-4fa4-a48b-402f7eea07da",
        "updatedAt" : ISODate("2017-12-21T17:53:46.710Z"),
        "createdAt" : ISODate("2017-12-21T17:53:46.710Z")
    }, {
        "token" : "4a26e0af-d8dd-412e-83fa-fddb209ac646",
        "updatedAt" : ISODate("2017-12-20T17:53:46.710Z"),
        "createdAt" : ISODate("2017-12-20T17:53:46.710Z")
    }, {
        "token" : "34c4fd55-aea9-441d-8e0e-a5fbd0377b48",
        "updatedAt" : ISODate("2017-12-19T17:53:46.710Z"),
        "createdAt" : ISODate("2017-12-19T17:53:46.710Z")
    }, {
        "token" : "c7d67571-8a99-48e8-a7bd-e210693ff119",
        "updatedAt" : ISODate("2017-12-18T17:53:46.710Z"),
        "createdAt" : ISODate("2017-12-18T17:53:46.710Z")
    }]
}

如何删除超过X小时的recoveryAttempts？