In Uplay PC
Open your friends list by clicking on Friends and groups at the top of the window.
To remove or block a friend, simply right-click or select the three dots next to the username and choose Remove friend or Block from the drop-down.
On the Ubisoft Club Website
There, you can find additional options for managing friends. You can search friends by username, import them from a linked account's friends list (Playstation or Xbox) and add people you have met in-game, even if you don't remember their names.
If you would like to remove a friend from this list, click on their entry. This will redirect you to their profile. On the right side of the profile, you will find a small Friend button. Click on it to reveal the Remove friend option.
If you encounter any issues managing your friends, feel free to contact us!