Though this process does not involve much effort, it can require more work to clear your recently watched movie titles if you do not know the correct functions with which to work.
Update : 2 really easy way to delete your Netflix history or recently watched
Update
Unfortunately, Some users reported that this feature/instructions are not working anymore. Netflix has disabled these features, and there are no official options to remove or hide the recently watched content on your Netflix account apart from removing your account and creating it again.
Instructions
1. Sign into the Netflix account that you use. Then, click on the “Your Queue” option with your computer mouse.
2. Go to the new page that comes up on your screen. Click on the blue tab that the word “Instant.” Go down the page until you reach the part of the page that displays the instant list, beneath the movies you recently watched portion of the page.
3. Go to “Remove.” Then click the “X” symbol adjacent to the names of movies you desire to remove from your list of recently watched titles.