To delete a custom column, perform the following:

1. At the top right corner of the columns, click the Pick columns icon. The Add/Remove Column pane appears.
2. Click the Custom column tab.
3. In the Search Columns box, search for the required custom column.
4. On the right side of the required custom column to be deleted, click the more icon. 
5. Click Delete. The delete custom calculation window appears.
6. Click Confirm.