Troubleshooting Column Deletion and Provider Changes in Waterfall

Deleting Column Failed-- Scenario: I applied waterfall for finding emails and mistakely selected Apollo enrichment (pre-enriched) as the first option. Moving on to other columns, formulas get values from this waterfall. Even if auto-update of the table is off and I want to delete the Apollo column or other columns of waterfall, it is giving error - deleting column failed