To disable comments on all posts/pages:
Go to Themify > Settings > Default Layouts, tick the "Disable comments in all Posts" or "Disable comments in all Pages" checkbox.
To disable comments on individual post/page:
When adding or editing a post/page, there should be a panel called "Discussion". If the Discussion panel is not visible, scroll to the top of the page and click "Screen Options", tick the "Discussion" checkbox, now the Discusion panel should be visible below the content box, uncheck "Allow comments" to disable comments on that post.