Hello @kwadwo,
Ad block in the header is handled by a sidebar called Header Ad Spot. To remove that block, you may want to remove widget from that sidebar.
If you want ad block to disappear only from home page, you should add provided CSS code to your Custom CSS section:
.home .header .adspot {
display:none;
}
Let me know if you have any problems.
Cheers,
Piotrek