Hi,
1. Go in the Display>Filters menu in HikaShop's backend and edit the sort by filter.
There, on the right side of the screen, you'll find an option with the list of choices of the filter and you can just delete the ones you don't want and save the filter.
2. These can be changed with translation overrides:
www.hikashop.com/forum/filters-search/89...rt-column-label.html
So for example, for Product name descending, you can add such translation override:
SORT_DESCENDING_PRODUCT_NAME="Name descending"