How to reset password of mysql to none?

http://dev.mysql.com/doc/refman/5.0/en/resetting-permissions.html

For Windows, use

mysql\bin>mysqld-nt --skip-grant-tables

C.5.4.1.3. Resetting the Root Password: Generic Instructions

The preceding sections provide password-resetting instructions for Windows and Unix systems. Alternatively, on any platform, you can set the new password using the mysql client (but this approach is less secure):

1. Stop mysqld and restart it with the --skip-grant-tables option. This enables anyone to connect without a password and with all privileges. Because this is insecure, you might want to use --skip-grant-tables in conjunction with --skip-networking to prevent remote clients from connecting.
2. Connect to the mysqld server with this command:

   shell> mysql
   

3. Issue the following statements in the mysql client. Replace the password with the password that you want to use.

   mysql> UPDATE mysql.user SET authentication_string=PASSWORD('MyNewPass')
       ->                   WHERE User='root';
   mysql> FLUSH PRIVILEGES;
   

   The FLUSH statement tells the server to reload the grant tables into memory so that it notices the password change.

You should now be able to connect to the MySQL server as root using the new password. Stop the server, then restart it normally (without the --skip-grant-tables and --skip-networking options).