Disable dhcp service in dnsmasq

I would like to use only dnsmasq to forward all dns requests to google's dns server and disable dhcp...

How can I achieve this result?

dnsmasq has dhcp server disabled by default. To enable it you have to uncomment dhcp-related lines in /etc/dnsmasq.conf

to forward all requests to 208.67.222.222 it's sufficient to add (without touching dnsmasq config) in /etc/resolv.conf:

nameserver 127.0.0.1 
# In order to configure dnsmasq to act as cache for the host on which  it
# is  running, put [as the first line] "nameserver  127.0.0.1" in /etc/resolv.conf to force
# local processes to send queries to dnsmasq. [...]
# dnsmasq is smart enough to ignore this line and forward all queries appropriately, 
# while all other applications will send all their queries to dnsmasq. 
nameserver 208.67.222.222

That's it :)

Just comment out the dhcp-related lines in your dnsmasq.conf file and then restart dnsmasq.