Hi there!
Thanks for your query.
Actually, Helix Ultimate framework or Artion template isn't designed to create an one page template and that's why it'll not support the functionality of an one page template. Since what you are asking for is a functionality of an One page template that's the reason why the menu isn't closing.
So, I would suggest you to use any of our onepage templates to get all the facilities of an one page template.
Custom support is strictly prohibited in our support policy and I can't do anything which breaks the policy. But what I can do I can suggest you something.
Please check this link: https://www.joomshaper.com/forum/question/15829
Hope this will help you.
Best Regards