I have a document, which has a normal cover. When I try to resize (upscale) a word in the first line after the header, this happens:
Now I do not want the header and footer deleted, what I want is to literally remove the header/footer function so I can make use of that unused space in the top/bottom of the page, I tried regulating the ruler but it doesn't make any difference at all.
You want to change the page margins (which include the top margin and bottom margin). This is described in several places, with tutorials.
Here is a useful one:
You can adjust the margins there. But keep in mind that printers also require margins, so there are limits to the amount of space you can use.