Block or mute someone

Block from the menu on a profile, or with Decline and block on a message request. Blocking hides your activities from each other, closes messaging both ways and removes any friendship. The other person is not notified.

Unblock from their profile or from Settings under Blocked people.

Muting is one-way: their activities leave your feed and they are not told. Messages and friendship are unaffected. Manage it in Settings under Muted people.