Block subdomain, allow main domain

[Ben]

My wee brain is refusing to help me this morning  

I'm beginning to host my sites on a specific domain (example.com), so the site website1.com actually lives at example.com/~website1/ or website1.example.com


What I'd like to do is block traffic that is visiting either of the example.com addresses, other than the properly domain website1.com - I'm thinking .htaccess?

Any ideas?

[Bradman]

301 redirect via .htaccess should do it?

[Ben]

Was hoping to do it overall, rather than site-by-site, but looks like that wouldn't work. Off to write some .htaccess files, me thinks!

[JasonD]

Disable mod_userdir or whatever allows that form of url in the first place.