I don't want the 'Join Here' button on my header - how do I get rid of it??

Hi guys,

I really want to get rid of the 'Join Here' button from my header (please see here - http://4.biz). But I can't seem to find anywhere in the admin section to disable it.

I am working in the 'Edu-Clean' theme.

Any advice on how to get rid of it would be greatly apprectiated.