yii\db\BaseActiveRecord::unlinkAll PHP Method

    public function unlinkAll($name, $delete = false)
    {
        $relation = $this->getRelation($name);
        if ($relation->via !== null) {
            if (is_array($relation->via)) {
                /* @var $viaRelation ActiveQuery */
                list($viaName, $viaRelation) = $relation->via;
                $viaClass = $viaRelation->modelClass;
                unset($this->_related[$viaName]);
            } else {
                $viaRelation = $relation->via;
                $viaTable = reset($relation->via->from);
            }
            $condition = [];
            $nulls = [];
            foreach ($viaRelation->link as $a => $b) {
                $nulls[$a] = null;
                $condition[$a] = $this->{$b};
            }
            if (!empty($viaRelation->where)) {
                $condition = ['and', $condition, $viaRelation->where];
            }
            if (is_array($relation->via)) {
                /* @var $viaClass ActiveRecordInterface */
                if ($delete) {
                    $viaClass::deleteAll($condition);
                } else {
                    $viaClass::updateAll($nulls, $condition);
                }
            } else {
                /* @var $viaTable string */
                /* @var $command Command */
                $command = static::getDb()->createCommand();
                if ($delete) {
                    $command->delete($viaTable, $condition)->execute();
                } else {
                    $command->update($viaTable, $nulls, $condition)->execute();
                }
            }
        } else {
            /* @var $relatedModel ActiveRecordInterface */
            $relatedModel = $relation->modelClass;
            if (!$delete && count($relation->link) === 1 && is_array($this->{$b = reset($relation->link)})) {
                // relation via array valued attribute
                $this->{$b} = [];
                $this->save(false);
            } else {
                $nulls = [];
                $condition = [];
                foreach ($relation->link as $a => $b) {
                    $nulls[$a] = null;
                    $condition[$a] = $this->{$b};
                }
                if (!empty($relation->where)) {
                    $condition = ['and', $condition, $relation->where];
                }
                if ($delete) {
                    $relatedModel::deleteAll($condition);
                } else {
                    $relatedModel::updateAll($nulls, $condition);
                }
            }
        }
        unset($this->_related[$name]);
    }