Deleting Custom Currencies
To delete custom currencies:
In your application, select Manage, and then System Settings. In System Settings, select Currencies.
Select a currency, then Actions, and then Delete.
You cannot delete the following currencies:
A standard currency. It is always locked.
An enabled currency. Disable the currency before deleting it.
If a currency is in use, an error message tells you where it is used and prevents you from deleting it.