Transactions cannot be deleted and must be reversed

If you encounter the error Transactions cannot be deleted and must be reversed

When trying to delete an Invoice or transaction, this will generally be caused by two reasons. 

Error Message: 

400 Bad Request 

{
"Name" : "TransactionsCannotBeDeleted",
"Message" : "Transactions cannot be deleted and must be reversed",
"AdditionalDetails" : "[Path]",
"ErrorCode" : 25003,
"Severity" : "Error"
}

1. There is a payment against the invoice which we need to delete first before the invoice.

2. The setting has been enabled - Transactions can't be changed they Must be reversed. This setting is located in the UI under Setup >>Preferences >> Security 

In order to resolve this we either need to delete the payment from the invoice first which will then allow us to delete the invoice or if the preference has been enabled in the settings we will need to reverse the invoice or remove this setting in order to delete the transaction. 

If you have any questions, feel to log a ticket with the Customisation & Integration Team.