From their profile
Open the person's profile, click the Friends button and choose Unfriend in the window that appears. Closing that window instead leaves everything as it was.
From Connections
Open Connections and go to Friends.
Find the person — the search box above the list helps.
Click the three dots beside their name and select Unfriend.
There's no confirmation here — it happens as soon as you click.
What changes, and what doesn't
The Add friend button comes back on their profile. But if you were also following them — and you almost certainly were, since sending the request followed them automatically — you still are. Their posts keep appearing in your feed until you unfollow separately.
If you change your mind, you can send a new friend request at any time; the person will need to accept it again.
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