open “config.inc.php” on your PMA folder.
add this line to prompt the authentication before login
$cfg['Servers'][$i]['auth_type'] = 'cookie';
/* $cfg['Servers'][$i]['user'] = 'root'; */
/* $cfg['Servers'][$i]['password'] = ''; */
OR manually define your authentication by this line
$cfg['Servers'][$i]['auth_type'] = 'config';
$cfg['Servers'][$i]['user'] = 'root';
$cfg['Servers'][$i]['password'] = 'yourpassword';
solved Access denied with localhost [closed]