discoverAndAddAccounts will create customers and deleteCustomer will remove them. As I was testing I created customers and now I don't have their IDs so I can't delete them.
I don't see a method for that on https://ipp.developer.intuit.com/index.php?title=0010_Intuit_Partner_Platform/0020_Aggregation_%26_Categorization_Apps/AggCat_API/0020_API_Documentation