How to remove out of sync slaves older than x days from server

Hi, Our puppet bootstraps temporary clusters that runs for couple of hours and then terminate. Those clusters leftovers remain on the puppet server who tries to contact them all the time. How can i remove outofsync leftovers that older then xdays (by script)? details: installation: foreman-installer-1.15.2 puppet version: puppet-server-3.8.7 Thanks in advance