sudo apt-get --purge remove mysql-server mysql-common mysql-client
sudo apt-get install mysql-server mysql-common mysql-client

mysqladmin -u root password your-new-password
sudo /etc/init.d/mysql restart

apt-get install mariadb-server

mysql> show variables like 'char%';
+--------------------------+----------------------------+
| Variable_name      | Value           |
+--------------------------+----------------------------+
| character_set_client   | utf8            |
| character_set_connection | utf8            |
| character_set_database  | latin1           |
| character_set_filesystem | binary           |
| character_set_results  | utf8            |
| character_set_server   | latin1           |
| character_set_system   | utf8            |
| character_sets_dir    | /usr/share/mysql/charsets/ |
+--------------------------+----------------------------+

mysql> show variables like 'collation%';
+----------------------+-------------------+
| Variable_name    | Value       |
+----------------------+-------------------+
| collation_connection | utf8_general_ci  |
| collation_database  | latin1_swedish_ci |
| collation_server   | latin1_swedish_ci |
+----------------------+-------------------+

sudo vim /etc/mysql/my.cnf

[mysqld]
collation-server = utf8_unicode_ci
init-connect='SET NAMES utf8'
character-set-server = utf8

service mysql restart

sudo mysql -u root

SELECT User,Host FROM mysql.user;
+------------------+-----------+
| User       | Host   |
+------------------+-----------+
| admin      | localhost |
| debian-sys-maint | localhost |
| magento_user   | localhost |
| mysql.sys    | localhost |
| root       | localhost |

mysql> DROP USER 'root'@'localhost';
Query OK, 0 rows affected (0,00 sec)

mysql> CREATE USER 'root'@'%' IDENTIFIED BY '123456';
Query OK, 0 rows affected (0,00 sec)

mysql> GRANT ALL PRIVILEGES ON *.* TO 'root'@'%' WITH GRANT OPTION;
Query OK, 0 rows affected (0,00 sec)

mysql> FLUSH PRIVILEGES;
Query OK, 0 rows affected (0,01 sec)

SET PASSWORD FOR root@'localhost' = PASSWORD('password');

UPDATE mysql.user SET Password=PASSWORD('newpwd') WHERE User='root';

USE mysql
UPDATE user SET Password = PASSWORD('newpwd')
WHERE Host = 'localhost' AND User = 'root';

USE mysql
UPDATE user SET Password = PASSWORD('newpwd')
WHERE Host = '%' AND User = 'root';