For some reasons you might have sent a friend request to someone else on Facebook accidentally or you sent a friend request to someone you knew and he / she refuses to confirm the request. You can easily cancel those sent requests.
I am sure you know or you might not know that Facebook bans a user from sending friend requests if too many of them where not confirmed. And i am quite sure you wouldn’t want to find yourself in sure situation.
In other to avoid your account from being banned, you need to be conscious of who you send friend request to. So that in-case you find out they didn’t accept your request, you can easily cancel it. Really cool huh?