Where is my WordPress configuration located and how can I edit it?

The WordPress configuration file is located in the WordPress installation directory with the name wp-config.php

You can edit the wp-config.php file from Plesk --> File Manager. Search the file, click on it, and from the top menu choose Edit.

You can download wp-config.php via FTP software and edit it in Notepad++. After editing, just upload your file to your server.