1. Navigate to Purchase Super User -> Setup -> Financials Accounting -> Control Purchasing Periods
After searching your required period from above screen Save it.
If you have access to My Oracle Support (http://support.oracle.com), check out the new Period Close Advisor: E-Business Suite (EBS) [ID 335.1] - this will provide guidance on recommended period end procedures for E-Business Release 12.x. It is intended to be generic and does not relate to a specific organization or industry. Step by step best practices with tips and troubleshooting references are provided to assist you through each phase.