There are a few things can do.
1.
If you can’t login to WordPress, can try using the cPanel->WordPress Manager by Softaculous.
Then click the Login button. Then in WordPress admin left menu go to the Users page. Can change the user email and password there. Can’t change the username but can add new users if needed.
2.
On that cPanel->WordPress Manager by Softaculous page there is also a Manage Users link next to the Login button, can try that to change the password too for any of the WordPress admin users.
3.
Can use email or username when logging into WordPress directly at:
eg. https://mydomain.com.au/wp-admin
So if you know the login username or email can also click the “Lost your password?” link on that WordPress direct login page to change the password:
eg. https://mydomain.com.au/wp-admin
