How to hide an item from a menu to logged out users (without a plugin)

Find the class or id of the menu item that you want to hide.
suppose the class of that menu is logged-in-menu

Then in header.php file of your theme before closing head tag use the below code

<style>
<?php if(! is_user_logged_in() ) : ?>
    .logged-in-menu{
        display: none;
    }
<?php endif; ?>
</style>