Go to Websites & Funnels and find your funnel or webpage. Go to the step or page you'd like to hide for example, a Thank you page.
Click "Edit in a New Tab"
Then select SEO metadata.
Then select Links & Tags.
Click 'Add' next to Custom Meta Tags
Type in 'robots' in the Name field.
Type 'noindex' in the Content field and click Add
Click Save and then Publish.