If you would like to stop someone from contacting you on Facebook, the social network offers a variety of privacy settings that can help you manage interaction with that user. Perhaps the most extreme form of restricting contact with another user is to block them.
When you block someone on Facebook, you essentially restrict that user from viewing your profile, sending you messages, tagging you, commenting on your Facebook activity, and sending you requests. It is important to note, however, that blocking someone is not a "cure all," and it may not prevent all communications or interactions with the user in apps or groups.
Block a User on Facebook
There are two easy ways of blocking someone on Facebook.
Click the lock button located at the top right of any Facebook page. Then click How do I stop someone from bothering me?
From here, simply enter the name or email address of the person you want to block, and click Block. Note that if you entered a name, you can simply select the specific person you'd like to block from the list that appears.
Users will not be notified when they have been blocked.
If the above method doesn't work, you can also block a user by going to their Profile Page and clicking the ellipsis (three small dots) located on their cover photo. Simply click the Block option in the drop down menu to apply your new settings.
N.B. Unblocking a Facebook user will not automatically reestablish your online friendship. If you block a friend and then unblock them, you will need to send them a new friend request.