Delete Lease From Dnsmasq in CentOS 7

dnsmasq keeps track of the DHCP leases it has in a file which is defined
by the dhcp-leasefile config option.

To delete a lease from dnsmasq, first stop dnsmasq

systemctl stop dnsmasq

Remove the lease from the file. On Ubuntu this lease file defaults to
/var/lib/misc/dnsmasq.leases

Once the lease is removed, start dnsmasq.

systemctl start dnsmasq