从嵌套数组golang mongodb中删除元素

I have this on my mongo database :

{
"_id" : ObjectId("585a60b45ba19c3eb2016a16"),
"userid" : ObjectId("585a60715ba19c3eb2016a14"),
"apps" : [
    {
        "name" : "Apptest",
        "packagename" : "com.test.ezfez",
        "iconurl" : "an_url",
        "visited" : 0,
        "category" : "category",
        "_id" : ObjectId("585a61405ba19c3eb2016a17")
    },
    {
        "name" : "test",
        "packagename" : "test.packagename",
        "iconurl" : "url",
        "visited" : 0,
        "category" : "",
        "_id" : ObjectId("588755025ba19c6f870282d7")
    }, ...

I want to remove on element from this array. I'm using golang and mgo.v2 driver and here is my code :

selector := bson.M{"userid": bson.ObjectIdHex("585a60715ba19c3eb2016a14")}
    update := bson.M{"$pull": bson.M{"apps": bson.ObjectIdHex("585a61405ba19c3eb2016a17")}}
    if err := uc.session.DB("API").C("aioapps").Update(selector, update); err != nil {
        fmt.Println(err)
        SendError(w, "Remove", "Error on delete app")
    } else {
        SendSuccess(w, "Remove", "Success")
    }

It goes on Success but does not delete the item when I check on mongodb. Can soemeone tell me what I'm doing wrong ? Thank you

maybe you need to specify the field name in apps object just like

update := bson.M{"$pull": bson.M{"apps": bson.M{"_id":bson.ObjectIdHex("585a61405ba19c3eb2016a17")}}}