To delete a duplicate
data item, a calculated data item, or a derived data item, right-click
the data item in the Data pane and then select
Delete.
Note: If the deleted data item
is used by a visualization, then a confirmation message appears. The
deleted item is removed from your visualizations.
Note: You cannot delete a data
item that is included in a hierarchy. You must remove the data item
from any hierarchies before you can delete the data item.