off(eventName, callback) {
    if (typeof callback !== 'function') {
      console.error('ASScroll: Function not provided as second parameter');
      return;
    }

    if (eventName === 'scroll') {
      src_e.off(Events.EXTERNALSCROLL, callback);
      return;
    }

    if (eventName === 'update') {
      src_e.off(Events.EXTERNALRAF, callback);
      return;
    }

    if (eventName === 'scrollEnd') {
      src_e.off(Events.SCROLLEND, callback);
      return;
    }

    console.warn(`ASScroll: "${eventName}" is not a valid event`);
  }
Remove an event listener.
@param {string} eventName Name of the event
@param {function} callback Callback function