Where can I view a list of deleted credits?

If you have the Credit Invoices feature enabled, you will be able to view a list of deleted credits by downloading the Credit Payments (under Analytics -> Exports) and selecting the "Reduction" action. 

 

The reduction action is used to remove a credit balance from a credit invoice. You will select this action to see all credits that were "deleted" from an account. 

 

We have more details about this export here.