If you have forgot the MySQL root password, can't remember or want to break in... you can reset the mysql database password from the command line in either OS X or Linux as long as you know the root user password of the following you are on
Stop MySQL
$ sudo /usr/local/mysql/support-files/mysql.server stop
Start it in safe mode
$ sudo mysqld_safe --skip-grant-tables
This will be an ongoing command until the process is finished so open another shell/terminal window, log in without a password
$ mysql -u root
UPDATE mysql.user SET authentication_string=PASSWORD('password') WHERE User='root';
Change the lowercase password to what you want – with single quotes.
$ FLUSH PRIVILEGES; \q
Start MySQL
$ sudo /usr/local/mysql/support-files/mysql.server start