Hello,
Unfortunately, there is no option to disable the mobile menu. You can diable only categories additional tab. In your case, I would recommend you to create a custom menu with the product categories https://docs.woocommerce.com/document/docs-menus/#section-6 in the Appearance > Menus and then choose this newly created menu with categories in the mobile menu settings (Theme Options > Header builder > Mobile menu), and just disable the Categories tab.
Regards