We have a request to Change the Translation Rate from Corporate rate to the Same Rate that we use fo

We have a request to Change the Translation Rate from Corporate rate to the Same Rate that we use for Corporate Revaluations Rates. When I try to change the rate I get the following error which makes sense to me

You cannot update the period end or average rate type after running translation. You must purge translated balances first.

My question is do I have to go back and Purge All Translated Balances or just the currect period in order to make this change