Ubuntu One comes with the commandline tool u1sdtool to control it.

Basically the gui control panel cannot quit the syncdaemon but can connect/disconnect it.

If you need to control syncdaemon start/stop it

you have u1sdtool --start and u1sdtool --quit

If you need to connect/disconnect it

you have u1sdtool --connect and u1sdtool --disconnect commands

See u1sdtool --help for all the available commands.

You can do connect/disconnect through control panel gui as well.

There is a indicator for ubuntuone as well: What Application Indicators are available?

If you need to disable ubuntuone from autostarting at login
Syncdaemon is autostart service. So if you just need to disable the autostart part when you login to your session. Go to /etc/xdg/autostart and do

sudo sed --in-place 's/NoDisplay=true/NoDisplay=false/g' ubuntuone-launch.desktop

and disable it from startup-applications