I've been sent an Excel spreadsheet with a weird first row. Some of the cells say "Column1", "Column2", etc., but I can't delete their contents. If I select the cell and hit backspace, it goes blank, but when I press return, it goes right back to saying "Column1".

I found another answer here that suggested this could be caused by "Cell validation", but the validation window says "Any value", and also "show alert" (and I'm not seeing an alert), so I don't think that's it.

The first row is white text on a blue background, if that means anything. The spreadsheet was sent to me in XLSX format, but I tried resaving as XLS and opening that, and it seems to make no difference.

This is with the "ribbon" version of Excel (they got rid of the Help menu so I don't know how to see what version number it is!).

Thanks!

Update: The Excel online help says to use ribbon Home tab -> Cells -> Delete -> ... to delete cells. When I select anything on the first row, this pop-up menu is dimmed. So maybe Excel doesn't think row 1 consists of "cells"? Though I don't know what else it would call them.

Update 2: I found it, kind of. If I click the "Design" tab in the ribbon, then uncheck "Header Row", then first row becomes a normal row of cells again. Unfortunately, the contents disappear entirely. I want to delete a few cells, not all 50+! And if I copy the first row before turning off "Header Row", it disappears from the clipboard when I uncheck that. So I kind of know what mode it's stuck in, but not a good way out of it.