src/js/assets/selectr/selectr.js
function(event, func) {
    this._events = this._events || {};
    if (event in this._events === false) return;
    this._events[event].splice(this._events[event].indexOf(func), 1);
  }
function(event, func) {
    this._events = this._events || {};
    if (event in this._events === false) return;
    this._events[event].splice(this._events[event].indexOf(func), 1);
  }
Remove custom event listener
@param  {String} event Event type
@param  {Function} func   Callback
@return {Void}