You can change the DB user password by deleting the DB user in the cpanel and then recreate the user for the DB with new password.
Please be careful you indeed delete the user of the DB and NOT the database itself. Also it is recommended to first check which rights the user has on the database so you can set these the same after you recreate the user.
Note: you have to change the configuration files of the scripts you use and update them with the new password!
You may also request a password change through the support desk, please mention the database and username you want to the password reset from.
