The following error is displayed when you try to delete a currency in Web TimeSheet. "Record Cannot Be Deleted.  Currency is used by one or more Task Rate Entries".

The error is displayed if the currency you are trying to delete is used as a default currency in any of the expense codes. A default currency for an expense code (of expense rate type) can be configured by editing an expense code.

Deselect the currency from the "Expense Rate" drop-down on the "Edit Expense Code" screen and select a different currency. We should then be able to delete the currency.