A family of Microsoft word processing software products for creating web, email, and print documents.
First, double-click the header area on any page in the section after the section break. On the Header & Footer Tools tab of the ribbon, click the Link to Previous button. You'll be prompted whether to "delete this header/footer and connect to the header/footer in the previous section". Click Yes. You'll now see the same header in both sections.
Now you can delete the section break, and the single combined section will have the same header as before.
> I can't even put a new header and footer in the document since the page numbers would not be correct.
That's a misconception. The page numbers are inherent in the document; the header only shows them or does not show them.