relational Database delete in laravel

I am setting up a two database table, sale item and sale. When an admin make an inventory multiple sale item can added. After complete my sale inventory, i want to delete sale but i do not want to delete sale item table. My Sale Item migration table is:

public function up()
 {
    Schema::create('sales_items', function (Blueprint $table) {
        $table->increments('id');
        $table->string('product_name');
        $table->string('product_price');
        $table->string('product_quantity');
        $table->string('product_discount');
        $table->string('total_price');
        $table->integer('status');
        $table->integer('sale_id')->unsigned();
        $table->foreign('sale_id')->references('id')->on('sales')- >onDelete('cascade');
        $table->timestamps();
    });
}

Sale migration table is:

public function up()
{
    Schema::create('sales', function (Blueprint $table) {
        $table->increments('id');
        $table->string('sale_status');
        $table->string('total_price');
        $table->string('due');
        $table->timestamps();
    });
}

SaleItem Model :

public function sales(){
    return $this->hasOne(Sale::class, 'id', 'sale_id');
}

Sale Model:

public function saleitems(){
    return $this->hasMany(SalesItem::class, 'sale_id', 'id');
}

Now, How can i delete Sale table without delete sale item table?

via Chebli Mohamed