Step # 1: Stop the MySQL server process.

Step # 2: Start the MySQL (mysqld) server/daemon process with the --skip-grant-tables option so that it will not prompt for a password.

Step # 3: Connect to the MySQL server as the root user.

Step # 4: Set a new root password.

Step # 5: Exit and restart the MySQL server.

Here are the commands you need to type for each step (log in as the root user):

Step # 1: Stop the MySQL service:

service mysqld stop

Output:

Stopping MySQL database server: mysqld.

Step # 2: Start the MySQL server w/o password:

mysqld_safe --skip-grant-tables &

Output:

[1] 5988
Starting mysqld daemon with databases from /var/lib/mysql
mysqld_safe[6025]: started

Step # 3: Connect to the MySQL server using the MySQL client:

mysql -u root

Output:

Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 56299
Server version: 5.6.34-1 (Debian)

Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.


mysql>

Step # 4: Set a new MySQL root user password:

MySQL 5.7.5 and earlier

mysql> use mysql;
mysql> update user set password=PASSWORD("go_password_vao_day") where User='root';
mysql> flush privileges;
mysql> quit