Can’t detect the object

Question

I made an API script, in this script has some basic functions well used. I am currently working on editing Intervalsapi:

var interval = {

    intervals: { },

    create: function(name, func, interval) {
        if(this.intervals[name] != null){
            c.e("[IntervalAPI] Interval with name `"+name+"` already exists!");
        }
        else {
            this.intervals[name] = setInterval(func, interval);
            c.t("IntervalAPI", "Interval `"+name+"` created. Total Intervals: " + _.size(this.intervals));
        }
    },

    delete: function(name){
        if(this.intervals[name] != null){
            clearInterval(this.intervals[name]);
            c.ti("IntervalAPI", "Interval `"+name+"` removed.");
        }
        else {
            c.te("IntervalAPI", "Interval `"+name+"` not found.");
        }
    },

    clear: function(){
        _.each(this.intervals, function(v,k){
            clearInterval(v);
            c.t("IntervalAPI", "Interval `"+k+"` removed.");
        });
    }
};

When I run interval.create("teste", function(){ c.l("Is a Console.Log")}, 1000); appears the message normally that interval has been added. However when I try to remove interval.delete("teste"); says undefined and consequently the message

[Intervalapi] Interval teste not found.

in interval.intervals has the object { test: ... } and is not returning.