Turn on the Show/hide button in the paragraph group on the Home tab of the Ribbon. This will cause the display of non-printing characters in your doc. You'll be able to see markers that indicate the end of paragraphs, marks for spaces, for tab characters, etc. usually an extra page is either a page break that needs to be deleted, or extra empty paragraphs at the end of the doc. Click in them and backspace to remove.

The Show/Hide button is a fundamental part of using Word. If you are not using this tool at least some of the time, you will never get very good at using Word, and you will be typing while blindfolded.