When you manually insert a page break in Word Online, it will look like this when you’re in Editing View:
You won’t see this in Reading View. In Reading View, manual page breaks show up as gaps between pages, just like automatic page breaks.
To delete a manual page break, follow these steps:
If you’re not in Editing View, click Edit Document > Edit in Word Online.
Select the page break.
Note: You can only delete the page breaks that you’ve added to your documents. You can’t delete the page breaks that Word adds automatically as text flows from one page to the next.