Go to More > Settings > Friends > Blocked Friends to unblock a friend.

Creating a Kakao Account secures one email address you can use to explore all of Kakao's applications and linked services. 

Go to More > Settings > Privacy > Kakao Account to create a Kakao account. With your Kakao account, you can restore your information including your friends list, recommended friends list, blocked friends list, hidden friends list, sent/received items, KakaoTalk ID, profile picture and status message. (Friends whose phone numbers are not saved in your contacts will be displayed under their set name.)  

* NOTE : You may only use one Kakao Account per mobile number (and vice versa); you may not set more than one number to your Kakao Account. It is possible to have more than one mobile number registered to separate Kakao Accounts using a separate email address. If you attempt to connect your Kakao Account to a different phone number than originally registered, you will automatically be unregistered from the account. 

- If you have changed your phone number and had your new phone number verified, and then attempt to re-connect with your previous Kakao account, then your previous KakaoTalk will be deleted.   

Go to the Find tab (the magnifying glass icon) > Find button > ID Search to find your friends by KakaoTalk ID.

KakaoTalk ID is an identification username used in place of a phone number. Users can easily search and add friends by KakaoTalk IDs instead of by phone number.  

From the Friends tab, long-tap the person you wish to block and select Block.

To block a person on the Recommended Friends list, long-tap the person you wish to block or tap Block on their mini-profile.

If you want to unblock someone, go to the Friends tab, tap the gear-shaped icon on the top-right corner and select Blocked Friends.

Go to the Find tab (the magnifying glass icon) and tap the Edit button on the top-right corner to edit your friends list.

The deleted users will be permanently removed from your recommended friends list.