The Purge Process option under the Administration tab allows you to change the PMDB Purge schedule or run the PMDB Purge process right away.
Alter Purge Schedule
When you select the Purge Schedule Details, you can set the Start Date and Time for the Purge Process, change the recurrence by weeks and the selected days.
Purge PMDB Now
When you select this option, the PMDB purge job is triggered as it was configured during the installation process.