If you downloaded a series there are often folders for each episode. Each episode folder often includes another folder called “Sample” with a short demo video file.
Series -> Season 01 -> Episode 01 -> Sample -> sample.mkv
To get rid of these you can use the “find” and “rm” command. To remove each sample folder with its content you have to use the remove command with an “-r”.
find -name "Sample" -exec rm -r "{}" \;