That whitespace is marked as the “banner area”. So if your theme has something to remove or hide the banner for a page, try that first.
If you want to get rid of it on specific pages, then CSS like the following would work:
.page-id-10 .restoneu-banner-area {
display: none;
}
10 is the ID of your about-us page. The Contact us page is ID 8. So this would remove it from both of them:
.page-id-10 .restoneu-banner-area,
.page-id-8 .restoneu-banner-area {
display: none;
}