Please read carefully the page of the blocked user. Some social networks do not allow for the removal of such user from your contacts list for various reasons, for example, if a user page was hacked by someone else. In such cases, usually there is a notification about how long the page will once again be restored and handed over to the user. Then you can either leave it in the contacts list, or delete by clicking on the appropriate button which becomes available on the page.
User pages that have removed the page on their own, usually have a button to delete them from your contacts list. It will be located under the place where previously was the avatar of the user. Also try deleting the user through your contact list, without going to his page.
Next to the name of each of your friends must be function keys, one of which is responsible for removal from the list of contacts. Please note that in the future you will have the opportunity to bring a friend to your list, if it is not entered in your contacts. Users from the black list can't see your page, write messages and add friends.
Write a message to the social network's administration with a request to remove friends from your blocked user. In some cases, the lock is the fault of the person who actually committed the wrongful acts, and then it can take a long time.
Tell the experts what you don't want the user to stay in your friends, and the administration will help to resolve this issue. You can also contact the user as soon as the opportunity arises, and ask him to remove you from my friends list myself.