delete category and subcategory with products by category id in PHP MYSQL

How to delete category and subcategory with products by category id  in PHP MYSQL

                                      or

PHP Function to delete all category subcategory and products by category id

    public function deleteSub($aTable,$cat_id) {

        $aSql = "SELECT * FROM {$aTable} WHERE parent_id = ".$cat_id;
        $results = mysqli_query($this->databaseLink,$aSql);
        while($child = mysqli_fetch_array($results))
        {
            $this->deleteSub($aTable,$child["id"]);
        }
        $request = "DELETE FROM {$aTable} WHERE id = ".$cat_id;
        $request2 = "DELETE FROM product WHERE cat_id=".$cat_id;
        mysqli_query($this->databaseLink,$request2);
        return mysqli_query($this->databaseLink,$request);
       }