Youtube: How to delete all liked videos at once from playlist

UPDATE: 08/12/2020

Now it is easy to delete all your likes.

• Login to your Google account.
• Go to this link: https://myactivity.google.com/page?utm_source=my-activity&hl=en_GB&page=youtube_likes
• On the left side of the page, you will find an option called "Delete All."

Note: This will delete your likes and dislikes on YouTube videos from all time. Your activity will be permanently deleted from your account and no longer tied to you.

Outdated Solution

How to remove all your liked videos in your "Liked Videos" playlist on YouTube. As you may already know, it is impossible to delete the "Liked Videos" playlist itself, so we will have to remove all the items in it. Doing that one by one will take a long time.

The below solution will help to remove all videos at once.

• Open YouTube.
• Click on the "Liked Videos" playlist.
• Click on the edit option (It will be under the playlist name).
• In the address bar, add the following to the URL: &advanced_settings=1&disable_polymer=1
• Open the browser console (by pressing Ctrl + Shift + J).
  • Chrome: Windows: Ctrl + Shift + J | Mac: Option + Cmd + J
  • Firefox: Windows: Ctrl + Shift + K | Mac: Option + Cmd + K
  • Opera: Windows: Ctrl + Shift + J | Mac: Option + Cmd + J
  • Edge: Press "F12" and then click on the "Console" tab.
  • Safari: Option + Cmd + C (You need to enable the "Develop menu". Go to Safari > Preferences > Advanced tab, and check the box next to "Show Develop menu in menu bar".)
• Insert the JavaScript code given below exactly as it shows.
• Reload the page and repeat the process until your playlist is cleared. (Alternatively, you can scroll down and click "Load More" to show more items before running the code again.)
• Done!

    var items = $('body').getElementsByClassName("pl-video-edit-remove-liked-video"); 
    for(var i = 0; i < items.length; i++){
        items[i].click();
    }