There are two "View" modes in FormCentral - "Page View" and "Web View". This is controlled from either the "View" menu or the menu on the bottom right corner of the Design tab.
"Web View" is for designing your form for the web/HTML. In "Web View" no page breaks are added automatically, only the ones that you add using the "Add Item" toolbar by choosing the far right item, "New Page":
You can delete a page break you have added by clicking the trash can icon in the page break:
The page breaks added in "Web View" are not shown in "Page View" and are used only in the web form and not the PDF.
"Page View" is for designing your form for PDF. For the PDF there are two kinds of page breaks, implicit ones that are placed by FormsCentral based on the page size for PDF (in Form Setup, defaults to portrait and Letter size) ensuring that content fits onto the page, and explicit ones that you define by inserting page breaks as shown above to customize where those page breaks fall.
The two views can both be used to customize your form so that it works in both web and PDF, the page breaks are unique to each view. If you have a page break you do not expect look in the corresponding view to correct the page breaks.