I started a Word document with page numbers in the lower part of every page. Then I changed my mind and preferred to put them in the upper part. So I opened the Insert>Page numbers dialog box, and choose "Header" in the dropdown menu.

Since I applied that change, I have page numbers on my headers all right, but the footer page numbers are still there. How do I remove them ?

Open the footer, select the page # field and press Delete.

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]

As I'm new to Word I'm not sure I get your instructions here.
I did the following : in the main menu, select View > Headers and footers.
This creates a small footer box in my document as shown in the attached image.`

But the page number in that box seems uneditable, pressing delete does not do anything.

Attached Images

example_footer.png (28.7 KB, 20 views)

Select the '93' and, if it's in a frame, the frame too, then press Delete.

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]

Further explanation...
In earlier versions of Word (and possibly Word 2011) page numbers were inserted using Frames. A frame will look like a little box when selected. It can be deleted along with the contents.

Frames and Textboxes in Microsoft Word
Dynamic page numbers, themselves, are fields. Page Numbers in Word 2007-2016

That was helpful, thank you.

You are welcome.