code: function(groupName, callback) {
          var url = this.getResourceUrl({ path: '/groups/' + groupName, user: null });
          request.del(this.getSignedResourceUrl('DELETE', url), callback);
  
          return this;
      }
docs: Delete the resource group with the given name
  
  @param {String} groupName Name of the group you want to delete
  @param {Function} callback
  @return {ImboClient}