Can't remove demo content

Whenever I create a new page and set it to use a template, the live page contains the demo content (photos, copy, etc.). However, when I go to edit the page, the editor appears as if there is no content on the page yet, so I can only add new content but can’t delete any demo content.

Specifically, I’m trying to create a page of photos (not a page of galleries, just of individual photos). Whenever I add photos, it treats them as if they are photo albums and they are just there with the demo content.

How do I delete demo content from a new page and (for bonus points) how do I create a page of individual photos instead of a page of galleries?