For the new YouTube layout try this instead Remove the YouTube Mixes items from youtube homepage by finding the element that contains the text "YouTube Mixes", and then deleting the 5th parent element. Simple but works as first addon. Real people's reviews:

• "Best add-on ever!!!!!!!!!!!111"
• "Ever since I downloaded Remove YouTube Mixes™ my life has changed, thank you!"
• "Not only I don't see the Mixes area on YouTube, but it also tripled my internet download speed! amazing!"
• "This add-on made me pass my finals!"