How can you edit the product grid template?

In order to edit the template, pop into Settings > Templates > Advanced > Edit Product Grid Template:

That will open up the code editor modal, and you can edit the contents of the template:

You can revert back to the default at any time using the Revert To Default button.  Once you're done, hit Save.  Remember that you also need to click the Use Custom Product Template toggle to enable it and then hit Save again.

Now go ahead and spot check your email.  In this example, I've removed the product name and price from the template: