speedy222

Search every username in your WordPress site from the author. Make the WP Search Username Widget active in your Widgets menu from your WordPress site.
Or place the below shortcode in your WordPress site page content:
[search-username]
Or place the php shortcode in your themes file with a FTP Program. You can find the normal and php shortcode in your shortcodes.txt file.
Option author page with FTP:
Only if you have not a author.php page in your themes then you can upload the author.php page from your plugin directory with a FTP program and save it up your pc directory. And upload it to your themes /wp-content/themes/your-theme-name/ directory with a FTP Program.

WP Search Username

Search every username from the author in your Wordpress site.

Benoti

Brozzme Change Username is a one click tool to modify any user username everywhere.
To apply a new name, you just need to to select an user and put its new username. 
This plugin will detet any user_login with an “admin” sequence. It will secure your WordPress from bots that will try to access to your WordPress back-office. 
This plugin doesn’t have any options settings.
Link to <a href="https://brozzme.com/" title="Brozzme" rel="nofollow ugc">Brozzme</a> and <a href="https://www.wpserveur.net/?refwps=221" title="WPServeur WordPress Hosting" rel="nofollow ugc">WPServeur</a>.

Brozzme Change Username

Easily change a WordPress Username, save time, increase security.

WP Search Username vs Brozzme Change Username