Can custom fields be deleted if data has been captured in said fields?
This feature is available on the Master payroll edition.
Custom Fields can be
deleted regardless of whether or not information has already been processed for
that particular field.
If information has been processed in the field that is being deleted, a pop-up message will appear to confirm the deletion (after the element is deleted, before the screen is updated).
Navigate > Configuration > Basic Settings > Custom Screens & Fields > Custom Fields > Fields > Saved Custom Fields