mysqladmin -u root password 'asdfghjkl'

[client]
password = asdfghjkl

ALTER USER 'root'@'localhost' IDENTIFIED BY 'MyNewPass'

update user set password=PASSWORD("") where User='root';

sudo service mysql restart

grant all privileges on *.* to 'root'@'localhost' identified by '';

#> mysqladmin -u root password ''

grant usage on *.* to 'root'@'localhost' identified via unix_socket;

some_user@box: mysql -u root  # denied
root@box: mysql               # good
some_user@box: sudo mysql     # good, if "some_user" has sudo rights.