RewriteEngine On
RewriteCond %{HTTP_HOST} ^old\.website\.com$ [NC]
RewriteRule ^ http://new.website.com%{REQUEST_URI} [L,R=301,NE]
But here the subdomain, if created via Directadmin is in created via https://www.test.com/demoin plesk it's very easy but here I see site redirection and I dont see subdomain only maindomain.