Deleteing of Entites which no longer needed

Summary:

Our Client have accumulate lot of inactive entities (100+) over the years and they would like to delete them from FCC becasue Once EOBP is enabled it results in running explicit additional consolidation for those inactive entities to change the status from impacted to OK. This results in an overhead of running consolidation for a period and locking the month

what is the best practice suggested by Oracle to delete the entities in FCC ?

Assumption : there is no data for the past 7 years from audit perspective . Will there be any impact if business want to unlock historical periods post deletion of entities to reclass data ?