updating the multiple image gets deleted non-updated image

i am doing ecommerce project ,for the product i have setup 4 images per products but while updating the product image it gets updated but non updated imge gets deleted my model is

    public function delete_images(){
        Storage::delete($this->product_image_1);
        Storage::delete($this->product_image_2);
        Storage::delete($this->product_image_3);
        Storage::delete($this->product_image_4);
    }

controller is

  public function update(editProductRequest $request, Products $product)
    {
        $data=$request->only([
                                'category_id',
                                'subcategory_id',
                                'brand_id',
                                'product_name',
                                'product_code',
                                'product_quantity',
                                'product_detail',
                                'product_color',
                                'product_size',
                                'selling_price',
                                'discount_price',
                                'video_link',
                                'main_slider',
                                'hot_deal',
                                'best_rated',
                                'mid_slider',
                                'hot_new',
                                'trend',

                                'status']);

        if($request->hasFile('product_image_1')){

            $product_image_1=$request->product_image_1->store('products','public');
            $product->delete_images();
            $data['product_image_1']=$product_image_1;

        }
        if($request->hasFile('product_image_2')){
            $product_image_2=$request->product_image_2->store('products','public');
            $product->delete_images();

            $data['product_image_2']=$product_image_2;

        }
        if($request->hasFile('product_image_3')){
            $product_image_3=$request->product_image_3->store('products','public');
            $product->delete_images();

            $data['product_image_3']=$product_image_3;

        }
        if($request->hasFile('product_image_4')){
            $product_image_4=$request->product_image_4->store('products','public');
            $product->delete_images();

            $data['product_image_4']=$product_image_4;

        }
        $product->update($data);
        toastr()->success('Product updated successfully');
        return redirect(route('products.index'));



    }

how can i correct it