How to remove videos from favourites in YouTube?

You can do it in 3 steps

1. Sign in to your YouTube account and click the link "Account" (top right corner of the page).
2. Under the "My Videos" section, click the "Favourites" link
3. Check the box next to the video you want to remove and click the "Remove Video" button.  
   

That's it. The video will be removed from your favorites.
Similar steps will remove videos from your playlists by clicking the"Playlists" link.