i have a path like www.example.com/forum where i had a vbulleting install. This subfolder "forum" is already assigned to my subdomain forum.example.com

now i changed the forum config so the root path for the forum is always forum.example.com.

But the old folder www.example.com/forum still exists and is my subdomains folder.

What do i do now so forum.example.com and www.example.com/forum does not get penalized - put a robots txt in it and disallow all....redirect..whatever?

the point is that the subfolder is still valid since it is the folder where the subdomain resides...