Multiple image sizes for every uploaded image.

It appears that the theme Enfold makes several image sizes of every image I upload. I understand what’s that’s for. But some of the image copies are really large (like 1300 px). My website is an art portfolio, and I intentionally don’t upload images larger than 800 px because it makes them harder to steal, which is a big problem for me.
It’s also making my image library quite big.

Is there a way to control how many duplicates are created, and in what sizes?
Is there an explanation in Enfold documentation that explains where these different sizes are used?