When you request a friend on Facebook and you delete it will the other person know?

[Duncan]

No, don't worry! When you get a request on Facebook, you'll see two options. There's the accept button and the ignore button. The ignore button is exactly what it says - you ignore the friend request. This means that they won't get a notification that you've ignored their friend request. In fact, they won't see any difference at all.

If you're the one that has sent the request, it will say on their profile page that you've sent a friend request. However, I've sometimes accidentally friend requested people that I didn't mean to. If you cancel the request by going to the drop down menu where it says "friend request sent" on their profile page, then the friend request will simply disappear. If they haven't already accepted the request, it will be removed and the two of you will remain unfriended.

If you're already friends, and you delete them, your profile will just disappear from their newsfeed and they won't be able to see all your posts anymore. Any comments you've made on their photos/statuses/ect will remain, but they can no longer comment on your things and you can no longer comment on theirs. However, they won't know you've removed them from your friends unless they go to view your profile, where it show that you're no longer friends.