As beautiful as NTP is, NTP chatter can pollute your network traffic.
Forget removing NTP services, that is too dramatic for the system. A simple hack is to edit the /etc/ntp.conf file and remove the servers.
sudo nano /etc/ntp.conf
scroll down and hash out the lines like below:
# You do need to talk to an NTP server or two (or three).
# pool.ntp.org maps to about 1000 low-stratum NTP servers. Your server will
# pick a different set every time it starts up. Please consider joining the
# pool: <http://www.pool.ntp.org/join.html>
#server 0.debian.pool.ntp.org iburst
#server 1.debian.pool.ntp.org iburst
#server 2.debian.pool.ntp.org iburst
#server 3.debian.pool.ntp.org iburst
Control-X and yes to save
sudo /etc/init.d/ntp restart