Changing Base Currency to an Existing BU

We are beginning an integration project which will require a handful of BU's to now have non-USD base currencies. All BU's were USD-based prior to now. The BU's that we would be changing do NOT have any GL activity, as data flows directly to EPM. After the integration, BU's will then begin to process thru GL with Multicurrency configured.

When attempting to change the base currency on these BU's we receive an error "Base Currency may not be changed once Ledgers have been entered for a Business Unit". The error message further explains that "To change this value delete the Ledgers assigned to this BU. Please not that Ledgers may not be not be deleted once entries to the ledger have been made....". When we attempt to delete the Ledger Group attached to the BU, it allows us to delete the row, as there's no entries posted to this BU, but when attempting to save we received the following