Deleting an Effectivity 
You can remove an effectivity from the DC in case it is not being used in any if-then rule.
Locate the Project Resources node (Where is the Project Resources node?) and double-click the node.
In the Project Resources editor that appears, choose the Effectivities tab.
In the effectivities editor, choose the effectivity name in the relevant column and choose the Delete button.
In the dialog box that appears, choose OK
Save the changes.