Remove admin color scheme picker and set default scheme for new user in wordpress

RemoveAdminColorScheme.php

<?php
add_action( 'init', function() {
	remove_action( 'admin_color_scheme_picker', 'admin_color_scheme_picker' );
});

add_action( 'user_register', function ($user_id) {
	wp_update_user([
		'ID' => $user_id,
		'admin_color' => 'Default' // Light | Blue | Midnight | Sunrise | Ectoplasm | Ocean | Coffee
	]);
});