In terminal, log in to MySQL as root. You may have created a root password when you installed MySQL for the first time or the password could be blank, in which case you can just press ENTER when prompted for a password. If you have forgotten your root password, you can always Reset the MySQL Root Password.
sudo mysql -p -u root
Now add a new MySQL user with the username of your choice. In this example we are calling it pmauser (for phpmyadmin user). Make sure to replace password_here with your own. You can generate a password here.
The % symbol here tells MySQL to allow this user to log in from anywhere remotely. If you wanted heightened security, you could replace this with an IP address.
CREATE USER 'pmauser'@'%' IDENTIFIED BY 'password_here';
Now we will grant superuser privilege to our new user.
GRANT ALL PRIVILEGES ON *.* TO 'pmauser'@'%' WITH GRANT OPTION;
You should now be able to access phpMyAdmin using this new user account.
Hope this helps! 😀