Remove/Hide a Widget on a Custom Template

The menu is most likely part of the file header.php, which is called from get_header(). To alter the header just for your custom template, you may create another header file (e.g. header-no-menu.php), and call it using get_header(‘no-menu’). Here’s a link to some documentation: http://codex.wordpress.org/Function_Reference/get_header
Hope that helps!