remove(section) {
    var index = this.spineItems.indexOf(section);

    if (index > -1) {
      delete this.spineByHref[section.href];
      delete this.spineById[section.idref];
      return this.spineItems.splice(index, 1);
    }
  }
Remove a Section from the Spine
@private
@param  {Section} section