How to change DB user password for CiviCRM 4.7.3?
Ok, I figured it out and for the benefit of anyone who might Google search this same question, here's the answer.
 1. Go to your webhost's file browser.
 2. The file should be located in /public_html/wp-content/uploads/civicrm/civicrm.settings.php
 3. Open the file with the code editor.
 4. Modify the credentials string which contains the password and save.