If you have added somebody as a friend to your Facebook account and for some reasons you do not want that user to interact with you or access your profile, then you can always block that user from accessing your Facebook Profile. When you block people, they will not be able to interact with you on Facebook. Any Facebook friendships or relationships you currently have with that person will be broken.
To block any person, go to the privacy settings (Click Account-> Privacy Settings). In the privacy settings, click on “Block List”.
Click on the Block list and you can use either the person name or the email ID to block a user. Type in the name or email ID and click Block user.
Once you have blocked, you can click on the Preview My Profile button on the top and enter the blocked user’s name and see how the account looks for that person. In case you want to unblock this person any time in the future, you can click on the unblock button from the list of users blocked.