Open the map and click on page 3. Click on the location so it turns yellow then right-click and you should see a menu which includes "Move to page", if you hover over that you should see two choices, Page 1 or Page 2. When you move the location to the page you chose, the current page should be deleted.
If you have an empty page, move an existing location to it. Do the above to move the location to the page the location was originally in and the empty page should be deleted.