Im not sure if there's an ACP option and I can't be bothered to check so:
Prosilver themes:
Open styles/yourtheme/template/index_body.html:
Find:
Delete that line.
Subsilver themes:
Open styles/yourtheme/template/index_body.html:
Find:
Delete that line.
Note: I have not tested these solutions but im sure they will work. I also take no responsibility for any damage these code changes may do to your forum, use at your own risk.