I will give the option of changing the root password of the user for MySQL.
Stop the MySQL server:
sudo /etc/init.d/mysql stop
sudo service mysql stop
Run mysqld without privilege and network support:
sudo mkdir -p /var/run/mysqld
sudo chown mysql:mysql /var/run/mysqld
sudo /usr/sbin/mysqld --skip-grant-tables --skip-networking &
jobs
Connect as root user without entering a password:
mysql -u root
Change password:
use mysql;
UPDATE mysql.user SET Password=PASSWORD('NEW_PASSWORD') WHERE User='root';
FLUSH PRIVILEGES;
exit;
Or so:
use mysql;
UPDATE user SET authentication_string=PASSWORD("NEW_PASSWORD") WHERE User='root';
UPDATE user SET plugin="mysql_native_password" WHERE User='root';
FLUSH PRIVILEGES;
exit;
Stop the mysqld process:
sudo pkill mysqld
jobs
Let’s start the MySQL server in normal mode:
sudo /etc/init.d/mysql start
sudo service mysql start
Done.
See also my articles:
How to change root password for MySQL
How to create a MySQL user and configure access rights