When you Delete a Response from your Zonka Feedback, the following happens. 

What happens to Number of Responses when you delete a Response?

The number of Responses goes down when you delete a response. So say you had 100 responses and you deleted 2, now your number of Responses would be 98. 

What happens to your Scores when you delete a Response?

The cumulative Customer Satisfaction Scores, i.e. Net Promoter Score, Customer Effort Score and Customer Satisfaction Score do not get affected by the deletion of a Response. The score continues to be the same and does not get updated.