Process

1. Stop the MySQL (mysqld) server/daemon process.
2. Start the MySQL server process the –skip-grant-tables option so that it will not prompt for a password: mysqld_safe --skip-grant-tables &
3. Connect to the MySQL server as the root user: mysql -u root
4. Change password:

• (5.7.6 and newer): ALTER USER 'root'@'localhost' IDENTIFIED BY 'new-password';
• (5.7.5 and older, or MariaDB): SET PASSWORD FOR 'root'@'localhost' = PASSWORD('new-password); flush privileges; quit;

1. Restart the MySQL server.

Note: this will work only if you are physically on the same server.

Online Doc: http://dev.mysql.com/doc/refman/5.7/en/resetting-permissions.html