Adding items to User Account Menu

If you want to add menu items under the User Account Menu, do the following:

\System\Classes\SettingsManager::instance()->registerCallback(function ($manager) {
    $manager->registerSettingItems('October.Backend', [
        'item1' => [
            'label'       => 'My Test Item',
            'url'         => Backend::url('<replace url here>'),
            'category'    => 'MyCategory',
            'context'     => 'mysettings',
        ],
        'item2' => [
            'label'       => 'My Test Item 2',
            'url'         => Backend::url('<replace url here>'),
            'category'    => 'MyCategory',
            'context'     => 'mysettings',
        ],
    ]);
});

Use removeSettingItem() method to remove items.