MYSQL

Edit the conf file 

sudo vi /etc/my.cnf

Add line to mysqld block.*

skip-grant-tables

Save and exit.

Restart MySQL service.

sudo systemctl restart mysqld

Check Service status

sudo systemctl status mysqld

Connect to My SQL

mysql

Switch main database.

use mysql;

Redefine user root password.

UPDATE user SET `authentication_string` = PASSWORD('mySuperSecretPassword1') WHERE `User` = 'root';

Edit file my.cnf.
sudo vi /etc/my.cnf

remove line  

skip-grant-tables

restart MYSQL Service