Hi, do I declare and instance of DataObject correctly? I tried this to delete a first found record but did not work,

$product = Product; or $product = Product;::create();
$product->get();
$product->delete();echo $product->ID;
$product->write();

I think the error is on delete.

instantiating a new Product object would be someting like this:

$product = new Product();
Or
$product = Product::create();

To get the first of a set of Products you could:

$product = Product::get()->first();

you could possibly even:

Product::get()->first()->delete();

A good starting point would be the docs, specifically here:
https://docs.silverstripe.org/en/3.1/developer_guides/model/data_model_and_orm/