I would recommend to use the Pre-Configured page instead of the Auto-generated page. You can decide which buttons display to the user. You can use conditions in the process based on the button the user clicks in the Pre-Configured page.
It's possible to hide "Close" button by applying custom CSS style to the AutoGeneratedPageV2 schema. In this way you need to find the correct selector for "Close" button in AutoGeneratedPageV2.
The article by the link below describes how to add custom CSS: