Hybris comes with an OOTB Electronics store. All the products have a Specs page with a long list of specs. Any anyone point to some documentation on how to add or remove one of those specs via impex and/or code?
I am not sure which exact page you have mentioned about. In general, all the product data related ImpEx files are in hybris ▸ bin ▸ modules ▸ b2c-accelerator ▸ electronicsstore ▸ resources ▸ electronicsstore ▸ import ▸ sampledata ▸ productCatalogs ▸ electronicsProductCatalog. Most likely, you are looking for products_en.impex
in this path.
You can insert new data or update the existing data by executing similar ImpEx. Check here for information on ImpEx syntax.