Block addon domain showing as a subdomain

Hello all,

I added a second domain on my server as an addon. Everything is fine but the problem is that the second site can be accessed from my main site in the form of a subdomain.

For example, my site is https://www.example.com and I created another domain https://www.another.com. I can access the second domain by going to another.example.com or example.com/another.

I used the re_write rule but it doesn’t work.

RewriteEngine On
RewriteCond %{HTTP_HOST} ^(www.)?domain.com$ [NC]
RewriteCond %{REQUEST_URI} ^/addonfolder/(.*)$
RewriteRule ^(.*)$ – [L,R=404]

Any help please?