Yes you can disable this menu. If you assign the user to just the Browser role in the security tab when you click on the "Manage" option for this folder the "New" button will be unavailable. These options are only available to people with Publish or Content Manager roles.
Is there any possibility to allow some users to create paginated reports but not Power BI reports and vice versa. My main aim is allow/not allow users to create KPIs, Power BI report, Mobile report, Paginated report (mix and match) based on user credentials or some other criteria.