Use the following procedure to reset the password for a database user.
NOTE: The cPanel user can be used to access all databases on a cPanel account. To learn how to reset the password for a cPanel user go here.
Login to cPanel
Click on the MySQL® Databases icon
Under the "Current users" section, click the "Change Password" button
NOTE: You'll need to update the password for any applications that access the database as well. You'll need to consult with your developer if you are unsure how to update the password for your applications.