If you want to remove these sub-navigation items, open your qa-styles.css file and paste the following code:
/* Remove Hot & Most Votes Sub-navigation */
/* Remove No Selected & No Upvoted Answer Sub-navigation */
or paste it on your Admin Custom CSS option instead.
I believe these are really useful for the site navigation as it helps users know what topic is trending and also helps your website users become more active and engaged in helping respond questions in the community.
I personally live on the No Selected and No Upvoted Answers either if it's here on Q2A or StackOverflow.
Unless you're just a reader gathering information, there's no point on looking for questions to answer if they already have a couple of answers in which one will eventually emerge as a correct answer. Hence I look for questions in No Selected and No Upvoted answers to help answer questions that have not been answered by the community or may not have gotten the deserved attention, and stay marinating away till' they get on the 'dead zone' ending up with no response.
This opens a whole other brunch on one of the reasons why people only post one question, get no response and never come back to the website derived by that course of actions, but you get my point.