Add some custom styling rules to your WordPress Dashboard with this snippet.
Add custom CSS to WordPress admin area
WordPress
// CSS, PHP
add_action('admin_head', 'guyPrimavera_admin_custom_css'); // Hook into admin_head
function guyPrimavera_admin_custom_css() {
echo '<style>
ul#adminmenu li#menu-dashboard {
display: none;
}
</style>';
}
Paste this snippet into your theme's functions.php or in a WordPress plugin.