I wanted to stop the mongod service running on system boot in Ubuntu. This service is starting the mongodb database.
To do that I used the following two methods:
1. sudo update-rc.d -f mongodb remove
2. Open /etc/init/ folder and comment the following lines in the mongo.conf file:
start on runlevel [2345]
stop on runlevel [06]
This will stop the service from running on start up.