Hello.
Please help me , I want to change mysql password without create again user.
You have two ways for that.
a) you can log in to PhpMyAdmin as root and change the user password;
b) use the mysql command in SSH:
mysql -e "UPDATE mysql.user SET Password=PASSWORD('%your_password%' WHERE User='%your_user%' ; FLUSH PRIVILEGES)"
Where: %your_user% - database user ; %your_password% - the new user password