Follow the below path to lock and unlock payroll.
Login to the greytHR application
Click Payroll >>Main >> Overview >> Select the Payroll Month >> on the right side bottom of the page you will get an option to lock and unlock the payroll.
Use the Unlock Payroll with caution. Once a locked Payroll is unlocked, the reports that are generated may not match with the original reports. In case you need to unlock, please verify all reports and compare with earlier generated reports. Ensure that they match and then re-lock the Payroll.