The following happens when you hide a friend:
• You can still receive chat messages from them.
• They will not appear in your friends list, and will be moved to the Hidden Users list.
• You will see their profile and Timeline updates.
Hiding a user does not remove them completely as a friend or friend recommendation. To do so, please see the following article:
To hide a friend:
1. Go to the Friends tab.
2. Tap the options icon at the top-right, then Edit Friends List.
3. Select the friends you want to hide.
4. Tap Hide.
To unhide a hidden friend:
1. Go to More > Settings.
2. Tap Friends.
3. Tap Hidden Users.
4. Tap Edit next to the friend you want to show again.
5. Tap Display to unhide the friend.
Tap here to open the Settings menu from your smartphone.
Note: It may take a while for the changes to take effect.
To archive a chat, please see the following article: