Remove the registration routes from config/auth.php and then create a config/fortify.php (paste the content from: vendor/laravel/fortify/config/fortify.php) which will override the default settings.
Inside config/fortify.php comment out the first element of features array (Features::registration()) then run php artisan optimize to clear config cache and routes cache.
Now all your removed routes should return 404, you can also check if those still exist with php artisan route:list
config/fortify.php:
<?php
use Laravel\Fortify\Features;
return [
'guard' => 'web',
'middleware' => ['web'],
'passwords' => 'users',
'username' => 'email',
'email' => 'email',
'views' => true,
'home' => '/home',
'prefix' => '',
'domain' => null,
'limiters' => [
'login' => null,
],
'features' => [
//Features::registration(),
Features::resetPasswords(),
Features::emailVerification(),
Features::updateProfileInformation(),
Features::updatePasswords(),
Features::twoFactorAuthentication(),
],
];