If you delete a relative time that is used by other relative times as a base, the Base Time value for those dependent relative times is automatically changed to NONE.
When you remove a relative time or a time range, any objects/displays that use the removed named time will automatically revert to the current time (default).
If you have not already done so, select Named Times from the Edit menu. The Named Time Editor appears.
Select the Relative Times tab or the Ranges tab as required.
Click once in the row you want to remove.
Click the Delete button . The named time is removed from the list.