Starter WP Theme heading

Check the Stylesheet.

No stylesheet in Edit Themes

1. Please provide a link to a page on your site where we can see this. Thanks.

2. What theme is this?

Theme Start WP

https://natchezms.us/wp

As you use a commercial theme and need support, please use their official support channel. We feel they are best equipped to support their products.

https://www.iograficathemes.com/premium-support/

To get rid of the space at the top

.site-branding { 
  display: none;
}

To add CSS: If you are using WordPress 4.7, use the “Custom CSS” option in the customizer. If your theme has a custom CSS option, use that to add the CSS shown above. If not, install the plugin Simple Custom CSS. Or, if you have Jetpack installed, enable its Custom CSS module.

Learn to use the Chrome Developer Tools to help you see and test changes to your CSS.