@gechmas
Note: please do not make duplicate posts ??
Where is your site hosted? Is it with a hosting company such as GoDaddy, HostGator, BlueHost, etc. or is this a local installation on your own computer using a local web server such as XAMPP, WAMP, MAMP, etc.
All of the ones mentioned above have, as Tara pointed out, a database administration tool called phpMyAdmin. The various hosts will have access to this in their hosting control panel somewhere (also note that cPanel
is a brand name of a popular hosting control panel).
Once you are in phpMyAdmin, find the database for your WP site in the left side bar and expand it if it isn’t already. You will see a list of the tables. Click on the wp_users one. In the content area, if it isn’t selected, click the Browse tab. There you will see the user name in the user_login column.