1 The person will not be notified
If you delete a friend request you received from someone, the person will not be notified that you deleted it.
2 They can send you another friend request
After deleting a friend request, the person who sent it will be able to send another request if they wish to.
3 They won't have access to your profile details
Choosing to ignore or delete a friend request will not compromise your personal details on your profile as the user will not be able to see them.
4 They will know you deleted the request
The person who sent the request will know that you deleted it when they find that they can send you another friend request.
5 The request will disappear
If you choose to ignore the friend request and not take an action, it will stay in your friend requests list; however, if you delete the request, it will disappear from your list.