The following procedure shows how to edit the posting period’s name, date ranges, active and locked fields in existing posting periods.
1) In the SAP Business One Main Menu, choose > Administration > System Initialization > Posting Periods.
2) Click Link Arrow next to the posting period you want to edit. The Posting Period window appears
3) You may change now the period’s name, date ranges and the fields Active and Locked.
4) Choose Update.