mysql -u root
mysql> SET PASSWORD FOR 'root'@'localhost' = PASSWORD('newpass');

mysqladmin -u root password "newpass"

mysqladmin -u root password oldpass "newpass"

mysql -u root
mysql> use mysql;
mysql> UPDATE user SET Password = PASSWORD('newpass') WHERE user = 'root';
mysql> FLUSH PRIVILEGES;

mysqld_safe --skip-grant-tables&
mysql -u root mysql
mysql> UPDATE user SET password=PASSWORD("new password") WHERE user='root';
mysql> FLUSH PRIVILEGES;