When you delete a friend request, the person who sent you the request won’t be notified and can’t send you another request for one year. To permanently stop that person from sending you another friend request, you can block them.
To delete a friend request:
  1. Go to facebook.com/find-friends.
  2. Click Delete or Delete Request.
Learn how to cancel a friend request that you sent, or unfriend someone you’re already friends with on Facebook.