If there are graphics (other than inline with text), click the ¶ button on the home tab as Graham described, then click each graphic and see if it is anchored to the page break. If so, drag the anchor to another paragraph. When there are no graphics anchored to the page break it may be possible to delete the manual page break.
Also, I believe tables with wrapping set to Around can have the same effect of making it difficult to delete a page break that immediately follows the table. If this is the case, click just before the page break and press Enter. This should result in the paragraph immediately after the table not having a page break, with the page break following that. Now try deleting the page break.
In most cases I prefer to format a paragraph with Page Break Before rather than inserting a manual page break. Just to be clear, I refer here only to manual page breaks, not section breaks.