Removing the recommended videos of YouTube is very easy, YouTube recommends videos by analysing your search history and watch history.So, removing these data helps you in clearing the recommended video section.
Sign in to your YouTube account
Scroll down to the bottom of the page and choose the history option
Now, choose clear all watch history confirm it and then refresh the page.
Navigate to search history tab, choose clear all search history confirm it and refresh the page.
This is the last step, search for some videos which you like to be seen in recommended section of youtube.
After finishing these steps sign out of the YouTube account and check your recommended section.