You can remove the WordPress installation through Softaculous. Softaculous will delete the files and the database for you. See the following link.
How to uninstall programs using Softaculous
To find your database for your WordPress, you can look it up in your wp-config.php file in your WordPress files.
1. Look in your wp-config.php file found in the installation directory of your WordPress site.
2. Your database name associated with this WordPress install will be labeled as:
/** The name of the database for WordPress */
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