In the customize toolbar window, there is a filter text box. If you type "-list", it temporarily removes all playlists (and a few others as well) from the available toolbar buttons.
That said, I requested a long time ago that there just be a checkbox to not show playlists instead of having to type that into the filter box every time. In the event it's a slow day for Matt and he is bored, perhaps he can add that to his to do list?
