Screen Options WordPress WYSIWYG

The content box is in a <div> with an ID of #postdivrich so you can hide it using CSS.

Probably the easiest thing to do is to add a settings option to an existing page so you can turn it off or on. The post below covers that in detail:

http://wpengineer.com/2139/adding-settings-to-an-existing-page-using-the-settings-api/

After you have the setting in place, you need to check for it and output CSS in the right place. Add this to functions.php:

if (get_option('paradise_hide_editor') == 'yes') {
    function paradise_hide_editor() {
        echo '
        <style type="text/css">
        #postdivrich {display: none}
        </style>';
    }
    add_action('admin_head', 'paradise_hide_editor');
}