Hi Shelagh,
Thanks for posting in the community. We are happy to help you.
According to your description, my understanding is that your colleague has promoted a page by clicking the "Promote" button on the toolbar and click "Post as News on this site".
If not, please point it out and let us know.
If so, you can try the following steps to demote the news page back to the site page.
- Go to the site> Site contents> Site Pages. You should see the page. If not, please go to the related location where the page is stored.
- Create a new view for this library. In the new view, please click "Add column" and select "Show or hide columns".
- Please find and tick the "Promoted State" column, and then click Apply (in the upper-left corner of the pane).
- Now, you can see the "Promoted State" column in the library. Please click "Edit in grid view" and change this page's value in the "Promoted State" column from 2 to 0.
For your reference: How to Demote News page from Team site and Remove it from Hub News Rollup

Additionally, if you are the SharePoint admin or IT department, you can run the PnP PowerShell to get this done.
For your reference:
How to Promote a Site Page to News Post in SharePoint Online?
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We look forward to your response. Thanks for your cooperation.
Sincerely,
George | Microsoft Community Moderator