Somehow your conversion tracking wasn't set up properly and you ended up with a bunch of false conversion data in your Google Ad Campaign. Obviously, you don't want Google Ad's smart bidding algorithm to use that data for optimizing the campaign.
So is there a way to delete the data?
In a way yes, you can use Google Ad's Data Exclusions so the conversion data is not used for Google's smart bidding algorithm.
Simply set the start date and end date for the data exclusion and you're all set!