Prevent CrashPlan service from starting automatically on reboot

Running your first suggestion, I got this result: 

usage: update-rc.d [-n] [-f] <basename> remove
update-rc.d [-n] <basename> defaults [NN | sNN kNN]
update-rc.d [-n] <basename> start|stop NN runlvl [runlvl] [...] .
-n: not really
-f: force

 So I tried this: 

update-rc.d crashplan remove

... and then it said this: 

update-rc.d: /etc/init.d/crashplan exists during rc.d purge (use -f to force)

 Not sure if I should do this. What do you think Stephen? Maybe something should be changed in /etc/init.d/crashplan instead? It looks like this:

#!/bin/sh
# Linux Standard Base comments
### BEGIN INIT INFO
# Provides:          CrashPlanEngine
# Required-Start:    $local_fs $network $remote_fs
# Required-Stop:     $local_fs $network $remote_fs
# Should-Start:
# Should-Stop:
# Default-Start:     2 3 4 5
# Default-Stop:      0 1 6
# Short-Description: CrashPlan Engine
# Description:       CrashPlan backup service engine
### END INIT INFO

#############################################################
# Init script for CrashPlanEngine
#############################################################

# Defaults
SCRIPTNAME=/usr/local/crashplan/bin/CrashPlanEngine

case "$1" in
start)
        $SCRIPTNAME start
        ;;
stop)
        $SCRIPTNAME stop
        ;;
restart)
        $SCRIPTNAME restart
        ;;
force-reload)
        $SCRIPTNAME force-reload
        ;;
status)
        $SCRIPTNAME status
        ;;
*)
        echo "Usage: $0 <start|stop|restart|force-reload|status>" >&2
        exit 3
        ;;
esac
exit 0