how would i remove the header text?

Hope that you have a custom template for using the overrides?

The simple way to do this(not the only way) is to use your stylesheet.css and edit this with the changes/additions highlighted

Code:
#tagline {
    color:#ffffff;
    font-size: 2em;
    text-align : center;
    vertical-align: middle;
    display: none;
    }