You can use Data Mining Designer to remove columns from a mining structure after the structure has already been created. Reasons to remove a mining structure column might include the following:
The mining structure contains multiple copies of a column and you want to avoid the use of duplicate data in a model.
The data should be protected, but drillthrough has been enabled.
The data is unused in modeling and should not be processed.
Deleting a column from the mining structure does not change the column in the data source view or in the external data; only metadata is deleted. However, when you change the columns used in a mining structure, you must reprocess the structure and any models based on it.
To remove a column from the mining structure
Select the Mining Structure tab in Data Mining Designer.
Expand the tree for the mining structure, to show all the columns.
Right-click the column that you want to delete, and then select Delete.
In the Delete Objects dialog box, click OK.