I am running a business and I have a forum on it but I do not want under 18's to access it due to that its for booking and to hire,

anyway what ive done is ive created a link that says "Leave (Iam not 18 or over)"
and this resolves in window.close,

example:

<html>

<body>
<p><a href="javascrip t:window.close( );">Leave (I am not 18 or...