The sections with multiple columns are delineated by Section breaks before & after. Any time you delete a Section break, the Section preceding the former break adopts the latter Section's layout. Thus, if you delete a Section break before the two-column portion, the preceding Section will adopt a two-column layout. Delete the break after the two-column Section and it will adopt the following Section's layout (typically a single column. If you delete both Section breaks you'll end up will all three 'merged' sections having the last one's layout. Your first page alone has seven Section breaks, plus column breaks. Without any columns, column breaks function as page breaks, pushing whatever follows to the next page. If you click on the ¶ symbol on the Ribbon's Home tab to display the formatting marks, you should be able to see all the Section breaks. Switching to Draft view will also make the column breaks more apparent.

On the whole, the document is a real mess (a by-product of your OCR process) which I why I suggested using Adobe's own export-to-Word functionality or, better still, obtaining the original documents from which the PDFs were created.

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