I set the lease time to 4 weeks but that did not release any addresses yet, so I edited the file that you mentioned and that did it for me..
The path on ClearOS 5 was actually. /var/misc/dnsmasq.leases.
Nick Howitt wrote:
Leases are held in /var/lib/dnsmasq/dnsmasq.leases. You may need to stop dnsmasq before you edit the file.
From the webconfig you can set the lease time to 4 weeks (in 6.x. I don't know about 5.x). If this is not enough, you can manually edit /etc/dnsmasq.d/dhcp.conf.