Reset MySQL or MariaDB Root password.

First, stop the database server.

If you use MySQL, type the following command and hit ENTER key.

$ sudo systemctl stop mysql

For MariaDB:

$ sudo systemctl stop mariadb

Next, restart the database server without permission-checking using the following command:

$ sudo mysqld_safe --skip-grant-tables &

Next, login to your MySQL/MariaDB server as root user:

$ mysql

At the mysql> or MariaDB [(none)]> prompt, run the following command to reset the root user password:

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

Replace password in the above command with your own password.

Then, type following commands to exit from the mysql console.

FLUSH PRIVILEGES;

exit

Finally, shutdown the running database server that you started earlier with --skip-grant-tablesoption. To do so, run:

$ sudo mysqladmin -u root -p shutdown

You will be asked to enter your mysql/mariadb root user password that you set in the previous step.

Enter password: 
[2]- Done sudo mysqld_safe --skip-grant-tables

Now, start mysql/mariadb service normally using command:

$ sudo systemctl start mysql

For MariaDB:

$ sudo systemctl start mariadb

Verify if the password has really been changed using the following command:

$ sudo mysql -u root -p

Chúc các bạn thành công!