She/he won't receive a notification that you unfriended her. If she checks her list of friends and doesn't see you listed, then she'll either know or she won't care! If you're not a good friend of the person, then I doubt she'd care either! I have a relative who keeps adding "friends" because she wants to have a huge number of friends who "like" her comments and photos. If someone dropped out, she'd never know! If you don't want to receive her posts, unfriend her, or snooze her posts for awhile (and just keep snoozing her!).