If you disable both datatexts on the minimap to have a simple square map, it will have a offset on the Y axis where the top datatext was. Maybe its the minimum(14px) height of that datatext, you cannot move the minimap to the top of the screen with that offset.

Also if you disable the top datatext there's no way to have the zone name in the minimap. You can get around this by installing a weakaura with the zone name and just place it inside the minimap frame, but the offset issue I've still haven't found a workaround it.