the easiest way with the hd menus is while in the grid tv schedule guide. use the left arrow (<) to highlight the channel name and number in the left hand column, then press select, arrow down twice (V) to hightlight "remove from channel list", and press select again.
once you page down/up to refresh the guide, the channel will be gone.
The truth will set you free. But not until it is finished with you. - David Foster Wallace