Memory growth with new additions to WordPress Multisite

Yes, you can drop the “My sites” menu from a plugin.

function admin_bar_menus_remove_my_sites() {
    remove_action( 'admin_bar_menu', 'wp_admin_bar_my_sites_menu', 20 );
}
add_action( 'add_admin_bar_menus', 'admin_bar_menus_remove_my_sites' );