How to use the now.removeGroup function in now

everyone.now.declineInvitation = function(email){
    console.log('declineInvitation...');
    
    var emailFrom = getEmailByClient(this.user.clientId);
    var groupName = 'group-' + email;
    //remove the group reference from the user group list
    removeGroupFromUser(email,groupName);
    //remove the group
    now.removeGroup(groupName);
    //notify group creator
    callUserFunction(email, 'notify', [emailFrom + ' rejected your invitation.','error']);
  };

group.now.saveResultBasket(group.now.resultBasket,function(isSaved) {
    //remove the group relation from every user when the group is removed
    for(var email in users) {
      user = getUser(email);
      if(user) {
        removeGroupFromUser(email,group.groupName);
      }
    }
    //remove the group
    now.removeGroup(group.groupName);
  });