How to Add and Remove Calculated Fields in Excel PivotTables
A calculated field is a new field that performs calculations based on existing fields in your PivotTable. For example, you could use a calculated field to find the average ticket sales using an existing total sales field and a field containing the number of tickets sold.
If you decide you don't need the calculated field in your PivotTable, it can be removed just like any other PivotTable field.
Uncheck the calculated field in the PivotTable Fields pane.
The calculated field is removed from the PivotTable; however, it remains in the field list to use again in the future.
If you want to remove the calculated field completely, you need to re-open the Insert Calculated Field dialog box, select the field you created in the Fields list, and click the Delete button.