Adldap\Objects\BatchModification::setAttribute PHP Method

    public function setAttribute($attribute)
    {
        $this->attribute = $attribute;
        return $this;
    }

 /**
  * Removes all members from the current group.
  *
  * @return bool
  */
 public function removeMembers()
 {
     $modification = new BatchModification();
     $modification->setAttribute($this->schema->member());
     $modification->setType(LDAP_MODIFY_BATCH_REMOVE_ALL);
     $this->addModification($modification);
     return $this->save();
 }