How can I use db transaction in laravel?

I try this :

public function destroy($id)
{
    DB::beginTransaction();
    try {
        $product = $this->product_repository->find($id);
        $result = $product->categories()->detach();
        if($result) {
            list($status,$instance) = $this->product_repository->delete($id);
        }
        DB::commit();
        return ['status'=>true,'data'=>$status];
    } catch (\Exception $e) {
        DB::rollback();
        return ['status'=>false, 'message'=>$e->getMessage()];
    }
}

If the code executed, $this->product_repository->delete($id) not work / not success delete.

But this : $product->categories()->detach();, it works / success deleted.

How to if delete product failed, delete category also failed?