I’d successfully hidden ’em distracting grid lines in Excel via (Ribbon) > View > Gridlines, but then I wanted to hide (similarly distracting) page breaks. As it turns out, this option is pretty well hidden:
File > Options > Advanced > Display options for this worksheet > Show page breaks
Also note that this option is set on a per-worksheet basis, so you’ll have to uncheck once for every worksheet you may have. Thankfully, there is a drop list 3 check boxes above, so just rinse and repeat.
Kudos to the ExtendOffice blog post for this enlightenment: https://www.extendoffice.com/documents/excel/602-excel-hide-page-breaks.html.