The first steps with a new editor or theme can be challenging, but it's worth it.
If you're a newbie with Elementor or you're experiencing difficulties editing the theme's demo content, we recommend you to save the page/post as a template before customise it: https://elementor.com/help/how-to-duplicate-an-elementor-page/
This way, you can immediately restore the demo content and start over if something goes wrong.
If you haven't done the step above and have messed up a page or global template, there's another solution:
Step 1: You have to set up a staging/developing location.
Step 2: Install and set up the theme and demo content.
Step 3: Save the page you need to restore as a template https://elementor.com/help/how-to-duplicate-an-elementor-page/
Step 4: Export the demo page/global template.
Step 5: Import the demo page/global template to your primary installation.