How do I demote a menu item in the admin menu?

Question

Many plugins create a top-level item in the admin menu, even though there is no need. (There is discussion of when to create a top-level item and when to create a sub-item on the codex.) This can lead to a cluttered admin menu:

I would like to make some of these items into a sub-item of 'Tools' or 'Settings', which is where I think the plugin author should have put them anyway.

The Admin Menu Editor plugin does this if you pay for the premium version, which is currently $29 a year for more than two sites. For the functionality I'm looking for, I'm not willing to pay that much.

Is there a way to unhook a menu item and then re-hook it to another menu using php?

I've done my searching but haven't found anything to do this.

Answer 1

Your question is very abstract. It actually vary form plugin to plugin how the organize the menu and pages. So it's kinda hard to know how the plugin developer has managed the pages in their code. By the way as far I understood, you need to remove the page by using remove_menu_page function. Here is an example of it-

function custom_menu_page_removing() {
    remove_menu_page( $menu_slug );
}
add_action( 'admin_menu', 'custom_menu_page_removing' );

Here you'll get a documentation. Please follow that.

Then you need to add the page to settings by using add_options_page. Here is

add_action( 'admin_menu', 'my_plugin_menu' );

function my_plugin_menu() {
    add_options_page( 
        'My Options',
        'My Plugin',
        'manage_options',
        'my-plugin.php',
        'my_plugin_page'
    );
}

And for adding to Tools menu use add_submenu_page.

The documentation is here.